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ENGIN.kMATH. 
SCIENCES  lib/ 


THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 


GIFT 


^xl' 


U.  S.  DEPARTMEI^T  OF  AGRICULTURE, 
WEATHER    BUREAU. 

BUIiliETIN  No.  11. 


I^EI^OI^T 


OF  THE 


INTINATIOML  MfflOROLOGICAL  COIRESS, 


HELD    AT 


CHICAGO,  ILL,  AUGUST  21-24, 1893, 


UNDER  THE  AUSPICES  OF  THE 


Congress  Auxiliary  of  the  World's  Columbian  Exposition. 


EDITED  BY 

OLIVER   li.  FASSIG, 

SECRETARY. 


Pnbllshed  by  authority  of  the  Secretary  of  Agrlculttire. 


WASHINGTON,  D.  C: 

WEATHER  BUREAU. 
1894. 


I 


Part  II  is  in  press.     It  will  contain  the  papers  of^ — 

Section  IV.  History  and  Bibliography. 

Section    V.  Agricultural  Meteorology. 

Section  YI.  Atmospheric  Electricity  and  Terrestrial 
Magnetism. 


LETTER    OF   TRANSMITTAL. 


U.  S.  Department  op  Agriculture, 

Weather  Bureau, 
Washington,  D.  C,  September-  9,  1893. 
Sir:  I  have  the  honor  to  transmit  herewith  a  document  entitled 
"  Report    of    the    International    Meteorological    Congress,   held   at 
Chicago,  111.,  August  21-24,  1893,"  and  to  recommend  its  publication 
as  Weather  Bureau  Bulletin  No.  11. 
Very  respectfully, 


Hon.  J.  Sterling  Morton, 

Secretary  of  Agriculture. 


Mark  W.  Harrington, 

Chief  of  Weather  Bureau. 


MathsmatJcai 
Sciences 
Liorary 

INTRODUCTION.       "^,''''  ^^ 

v.i 


The  Congress  Auxiliary  of  the  World's  Columbian  Exposition  was 
organized  by  authority  and  with  the  support  of  the  Exposition  Cor- 
poration for  the  purpose  of  bringing  about  a  series  of  conventions  of 
leaders  of  the  various  departments  of  human  thought. 

The  various  congresses  held  their  sessions  in  the  Memorial  Art 
Palace  in  the  city  of  Chicago,  from  May  until  October,  1893 ;  those 
in  the  Department  of  Science  and  Philosophy  were  assigned  to  the 
week  commencing  August  21.  In  this  department  provision  was 
made  for  a  congress  on  Meteorology,  Climatology,  and  Terrestrial 
Magnetism.  In  November,  1892,  the  President  of  the  Congress  Aux- 
iliary, Mr.  C.  C.  Bonney,  invited  the  Chief  of  the  Weather  Bureau 
to  organize  such  a  congress.  In  accordance  with  this  request,  I  called 
a  conference  of  gentlemen  to  consult  with  me  in  the  arrangement  of 
a  programme.  The  following  persons  responded  to  the  call  and  met 
me  at  my  office  on  December  21 :  Professors  Cleveland  Abbe,  F.  H. 
Bigelow,  Thomas  Russell,  C.  A.  Schott,  Lieut.  Commodore  Richardson 
Clover,  and  Mr.  0.  L.  Fassig. 

As  a  final  result  of  the  conference  the  organization  indicated  on 
page  iv  was  effected  and  the  programme  shown  in  the  Table  of  Con- 
tents was  arranged.  The  papers  to  be  submitted  were  to  be  of  a 
strictly  scientific  character.  Authors  of  papers  were  to  be  requested 
to  present  in  the  best  manner  the  present  state  of  our  knowledge  of 
the  particular  branch  of  the  science  under  consideration. 

It  was  the  purpose  of  the  officers  of  the  Congress  Auxiliary  to  print 
in  the  English  language  all  papers  read  at  the  various  conferences, 
together  with  an  account  of  the  daily  proceedings.  As  this  purpose 
could  not  be  fulfilled  by  the  Auxiliary,  and  as  it  was  considered 
desirable  to  publish  the  papers  of  the  meteorological  congress  as  soon 
as  practicable,  other  means  of  publication  had  to  be  sought.  The 
matter  was  presented  to  the  Secretary  of  Agriculture,  the  Hon, 
J.  Sterling  Morton,  who  approved  the  publication  of  the  papers  as  a 
bulletin  of  the  U.  S.  Weather  Bureau. 

The  failure  of  the  Auxiliary  to  provide  translators  for  the  many 
papers  written  in  foreign  languages  caused  the  labor  of  translation  to 
devolve  upon  the  chairmen  of  the  sections ;  to  these  gentlemen,  as 
well  as  to  Prof.  Alexander  Ziwet,  of  the  University  of  Michigan,  and 
to  Mr.  Robert  Seyboth,  of  the  Weather  Bureau,  I  desire  to  express  my 
obligation  for  their  generous  assistance. 

Mark  W.  Harrington, 

Chairman. 


ORGANIZATION. 


O-ENBRAL    COMMITTEE. 

CHAIRMAN. 
Mark  W.  Harrington,  Chief  of  U.  S.  Weather  Bureau,  Washington,  D.  C. 

VICE-CHAIRMAN. 
Dr.  H.  C  Prankenfleld,  Local  Forecast  OflBcial,  Chicago,  111. 

SECRETARY. 
Oliver  Li.  Fasslg,  Librarian,  U.  S.  Weather  Bureau,  Washington  D.  C. 
MEMBERS    OF    THE    COMMITTEE. 

Prof.  Cleveland  Abbe,  Weather  Bureau,  Washington,  D.  C,  Chairman  of  Sec- 
tion on  Theoretical  Meteorology. 

tileut.  W.  H.  Beebler,  U.  S.  Navy,  Hydrographic  Office,  Washington,  D.  C, 
Chairman  of  Section  on  Marine  Meteorology. 

Prof.  F.  H.  Blgelow,  Weather  Bureau,  Washington,  D.  C,  Chairman  of  Section 
on  Atmospheric  Electricity  and  Terrestrial  Magnetism. 

Prof.  Chai'les  Carpmael,  Director  Canadian  Meteorological  Service,  Toronto; 

Mr.  A.  Lawrence  Rotcb,  Director  of  Blue  Hill  Observatory,  Boston,  Mass. ; 
Chairmen  of  Section  on  National  Weather  Services. 

Maj.  H.  H.  C.  Dunwoody,  U.  S.  Army.,  Weather  Bureau,  Washington,  D.  C, 
Chairman  of  Section  on  Agricultural  Meteorology. 

Mr.  Oliver  Ij.  Fassig,  Washington,  D.  C,  Chairman  of  Section  on  History  and 
Bibliography. 

Prof.  F.  B.  Nipher,  Washington  University,  St.  Louis,  Mo.,  Chairman  of  Sec- 
tion on  Climatology. 

Prof.  Thomas  Russell,  Office  of  U.   S.  Engineers,  Sault  Ste.   Marie,   Mich., 
Chairman  of  Section  on  Rivers  and  Floods. 

Prof.  C.  A.  Scliott,  Coast  and  Geodetic  Survey,  Washington,  D.  C. ; 

Mr.  H.  H.  Clayton,  Boston,  Mass.; 

Chairmen  of  Section  on  Instruments  and  Methods. 

LOOAIi  OOMMITTEB. 
(CHICAOO.) 

R.  Grigsby  Chandler.  W.  S.  Jackman. 

Elias  Colbert.  William  S.  Seaverns. 

OsBiAN  Guthrie.  Charles  B.  Thwinq. 


MINUTES   OF  THE  PROCEEDINGS. 


Memorial  Art  Institute, 
Chicago,  III.,  Monday,  August  21,  1893. 

Monday,  August  21,  at  10  a.  m.,  the  congresses  of  the  Department 
of  Science  and  Philosophy  were  formally  opened  at  the  Memorial 
Art  Institute  with  an  address  of  welcome  by  Mr.  C.  C.  Bonney,  Pres- 
ident of  the  Congress  Auxiliary  of  the  Columbian  Exposition.  At 
the  close  of  this  general  session,  which  lasted  about  one  hour,  the 
special  congresses  met  in  rooms  assigned  to  them  for  organization 
and  the  reading  and  discussion  of  papers. 

The  Congress  on  Meteorology,  Climatology,  and  Terrestrial  Mag- 
netism met  in  room  No.  31,  in  which  the  regular  sessions  were  held 
daily,  from  August  21  to  August  24. 

At  11  a.  m..  Prof.  F.  H.  Bigelow,  in  the  unavoidable  absence  of  the 
Chairman,  Prof.  Mark  W.  Harrington,  opened  the  Congress,  welcoming 
the  members  and  briefly  stating  its  objects.  The  Congress  had  no 
legislative  authority.  The  main  purpose  was  to  collect  a  series  of 
memoirs  prepared  by  writers  of  recognized  merit  in  their  respective 
fields  of  labor,  outlining  the  progress  and  summarizing  the  present 
state  of  knowledge  of  the  subject  treated.  These  reports  are  to  be 
printed  in  full  in  the  English  language,  and  will  form  a  record  of 
great  and  permanent  value  in  the  science  of  meteorology. 

At  the  conclusion  of  Prof.  Bigelow's  remarks  Capt.  A.  P.  Pinheiro, 
Director  of  the  Brazilian  Meteorological  Service,  was  called  upon  to 
read  his  paper  upon  "  Storms  in  the  South  Atlantic." ' 

Owing  to  the  great  number  of  papers  and  the  absence  of  authors, 
the  papers  were  largely  read  in  abstract  or  by  title  by  the  chairmen 
of  the  respective  sections. 

Lieut.  Beehler,  chairman  of  the  section  devoted  to  marine  meteor- 
ology, read  in  abstract  the  following  papers : 

"  The  forecasting  of  ocean  storms  and  the  best  method  of  making 
such  forecasts  available,"  by  William  Allingham,  Loudon. 

"The  secular  change  of  variation  of  the  mariner's  compass,"  by 
G.  W.  Littlehales,  Washington,  D.  C. 

"  Ocean  temperatures  and  ocean  currents,"  by  Lieut.  A.  Hautreux, 
Paris. 

*  As  all  papers  presented  to  the  Congress  are  printed  in  full  in  the  following  pages,  no 
abstracts  are  given  in  the  account  of  the  daily  proceedings. 


Viii  CHICAGO    METEOROLOGICAL    CONGRESS. 

"  The  creation  of  meteorological  observatories  on  islands  scattered 
over  the  ocean,"  by  the  Prince  Sovereign  of  Monaco. 

"The  barometer  at  sea,"  by  T.  S.  O'Leary,  Washington,  D.  C. 

Mr.  Fassig,  chairman  of  the  section  on  history  and  bibliography, 
presented  for  reading  two  papers  of  his  section : 

"The  meteorological  work  of  the  Smithsonian  Institution,"  by  the 
Secretary  of  the  Smithsonian  Institution,  read  by  Mr.  H.  H.  Clayton. 

"The  meteorological  work  of  the  office  of  the  Surgeon  General, 
U.  S.  Army,"  by  Maj.  Charles  Smart,  read  by  Mr.  Fassig. 

Prof.  Charles  Carpmeal  followed  with  the  reading  of  abstracts  of 
the  following  papers  of  the  section  devoted  to  national  services  and 
methods,  of  which  he  is  one  of  the  chairmen : 

■'The  publication  of  daily  weather  maps  and  bulletins,"  by  Mr. 
R.  H.  Scott,  of  London. 

"  Can  we  by  automatic  records  at  three  selected  stations  determine 
the  energy  of  a  flash  of  lightning  ?  "  by  A.  McAdie,  of  Washington, 
D.  C. 

"  The  utilization  of  cloud  observations  in  local  and  general  weather 
predictions,"  by  A.  McAdie,  of  Washington,  D.  C. 

Adjourned,  at  1.30  p.  m.,  to  meet  Tuesday,  at  10  a.  m. 


Tuesday,  Augibst  22,  1893. 

The  meeting  was  opened  at  10  a.  m.  by  the  Chairman,  Prof.  Mark 
W.  Harrington.  The  first  paper  of  the  day  was  by  Lieut.  Beehler 
on  "  The  meteorological  work  of  the  Hydrographic  Office  of  the  U.  S. 
Navy."  During  the  reading  of  this  paper,  which  was  devoted  largely 
to  the  work  of  Commodore  Maury,  Lieut.  Beehler  had  placed  upon  a 
pedestal,  for  inspection,  a  fine  bust  of  the  commodore  by  the  sculptor 
Valentine,  of  Richmond,  Va. 

Prof.  Lemstrom,  of  Helsingfors,  moved  to  hold  a  preliminary  in- 
formal session  at  10  a.  m.,  Wednesday,  to  decide  upon  a  programme 
for  the  day,  the  formal  session  to  begin  at  10.30  a.  m.  This  was 
agreed  to. 

Prof.  Mascart,  of  Paris,  then  gave  a  resume  of  his  paper  on  "  Op- 
tical phenomena,"  referring  particularly  to  the  explanation  of  the 
white  rainbow.  He  also  gave  a  resume  of  M.  Chauveau's  paper  on 
"  Instruments  for  the  observation  of  atmospheric  electricity." 

Capt.  Pinheiro  was  called  to  the  chair  while  Prof.  Harrington  read 
his  paper  on  "  The  history  of  the  daily  weather  map." 

Two  papers  by  Maj.  Dun  woody,  of  the  U.  S.  Weather  Bureau,  were 
presented,  "  Functions  of  state  weather  services  "  and  "  State  weather 
services  of  the  United  States."  Upon  motion  of  Mr.  Fassig,  the  del- 
egates to  the  Convention  of  Directors  of  State  Weather  Services,  who 
were  in  session  in  an  adjoining  room,  were  invited  to  be  present  at 


MINUTES    OF    THE    PROCEEDINGS.  IX 

the  reading  of  these  papers ;  the  invitation  was  accepted  and  the  del- 
egates attended  in  a  body.     At  the  close  of  the  readings,  Dr.  Duncan, 
of  Chicago,  made  some  remarks  upon  the  possibility  of  predicting 
epidemics  as  a  result  of  the  development  of  State  weather  services. 
Adjourned  at  2  p.  m. 


Wednesday,  August  23,  1893. 

The  informal  conference  agreed  upon  on  the  preceding  day  was 
held  at  10.15  a.  m.  It  was  decided  to  read  first  the  papers  whose 
authors  were  present ;  then  the  chairman  of  sections  were  to  present 
the  papers  of  their  respective  sections  of  which  abstracts  had  been 
previously  prepared. 

At  10.30  the  reading  of  papers  was  resumed.  Prof.  Harrington 
requested  Lieut.  Beehler  to  take  the  chair. 

Prof.  Carpmael  continued  the  reading  of  the  papers  of  his  section, 
as  follows : 

"  The  prediction  of  droughts  in  India,"  by  W.  L.  Dallas,  of  Calcutta. 

"  Plan  for  the  prediction  of  floods,"  by  M.  Babinet,  of  Paris. 

Dr.  Veeder,  of  Lyons,  N.  Y.,  read  a  paper  on  "An  international 
cipher  code  for  correspondence  relating  to  auroras  and  magnetic 
disturbances." 

Prof.  Bigelow,  chairman  of  the  section  on  atmospheric  electricity 
and  terrestrial  magnetism,  presented  the  papers  of  his  section,  read- 
ing some  by  title,  some  in  abstract.  He  read  at  length  his  paper  on 
"  The  magnetic  action  of  the  sun  upon  the  earth,"  and  it  was  discussed 
by  those  present. 

Father  Faura,  of  the  Manila  Observatory,  presented  a  paper  upon 
"  Signs  preceding  typhoons  in  the  Philippine  Islands."  Father  Faura 
also  laid  before  the  members  an  elaborate  printed  report  upon  ter- 
restrial magnetism  in  the  Philippine  Islands,  prepared  by  P.  R. 
Cirera,  S.  J.,  Director  of  the  magnetic  section  of  Manila  Observatory. 
Copies  of  this  report  were  distributed  at  the  close  of  the  session. 

Prof.  Lemstrom,  of  Helsingfors,  offered  a  resolution  proposing  that 
the  Congress  be  divided  into  four  sections,  in  which  there  should  be  a 
discussion  as  to  the  most  important  questions  pressing  for  solution, 
and  that  these  sections  place  before  the  General  Congress  a  recommen- 
dation as  to  the  method  of  carrying  on  the  necessary  observations  or 
investigations,  the  General  Congress  to  discuss  such  recommendations 
and  take  action  thereon.  The  proposition  was  not  agreed  to,  as  such 
action  would  be  foreign  to  the  purpose  of  the  Congress. 

Adjourned  at  1.45  p.  m. 


X  CHICAGO    METEOROLOGICAL   CONGRESS. 

Thursday,  August  24,  1893. 

The  meeting  was  opened  as  usual  in  room  No.  31,  at  10.20  a.  m., 
Lieutenant  Beehler  in  the  chair. 

The  first  paper  of  the  day  was  by  Father  Denza  on  "Alpine  meteo- 
rology," read  in  abstract  by  Father  Alque. 

Mr.  Rotch,  associate  chairman  of  the  section  devoted  to  national 
services,  read,  in  abstract,  the  following  papers  of  his  section : 

'•  Meteorological  stations  and  the  publication  of  results  of  observa- 
tions," by  Dr.  J.  Hann,  of  Vienna. 

"  Present  conditions  of  the  weather  service — propositions  for  its 
improvement,"  by  Dr.  W.  J.  van  Bebber,  of  Berlin. 

"The  best  method  of  testing  weather  predictions,"  by  Dr.  W. 
Koppen,  of  Hamburg. 

Prof.  Bigelow  then  took  the  chair. 

In  connection  with  the  reading  of  Dr.  van  Bebber's  paper.  Prof. 
Carpmael  suggested  that  a  statement  describing  the  method  employed 
by  the  U.  S.  Weather  Bureau  in  forecasting  the  weather  be  prepared 
and  sent  to  Dr.  van  Bebber  to  be  added  to  his  paper ;  that  he  would 
likewise  prepare  a  statement  describing  the  method  employed  by  the 
Canadian  Service.  This  w^ould  add  greatly  to  the  interest  and  value 
of  Dr.  van  Bebber's  paper  when  published. 

Prof.  Lemstrom  then  read  a  paper  by  Prof.  Lindelof ,  of  Helsingf ors, 
upon  "  The  influence  of  the  rotation  of  the  earth  on  movements  at  its 
surface,  etc."  This  was  followed  by  a  paper  of  his  own  on  "  The 
cosmical  relations  manifested  in  the  simultaneous  disturbances  of  the 
sun,  the  aurora,  and  the  terrestrial  magnetic  field." 

The  following  resolution,  offered  by  Lieut.  Beehler,  was  then  read 
and  agreed  to : 

Recognizing  that  the  members  of  this  Congress  do  not  possess  leg- 
islative powers,  be  it  resolved  that  the  following  statement  be  added 
to  the  official  report  of  the  proceedings :  In  view  of  the  importance 
of  a  number  of  the  papers  read  before  the  Congress  and  impressed 
with  the  desire  of  international  consideration  of  certain  questions,  we 
request  special  attention  to  the  following  points : 

1.  International  co-operation  in  observations  of  auroras. 

2.  Simultaneous  observations  at  the  instant  of  Greenwich  Noon,  by 
all  observers  on  land  and  at  sea  independent  of,  and  in  addition  to, 
all  other  observations. 

3.  Investigation  of  the  earth's  magnetic  polar  field,  and  exact  de- 
termination of  the  period  of  solar  rotation. 

Mr.  Fassig,  chairman  of  the  section  on  history  and  bibliography, 
then  read  abstracts  of  the  following  papers  of  his  section  : 

"Contribution  to  the  bibliography  of  meteorology  in  the  fifteenth 
to  the  seventeenth  centuries,"  by  Dr.  Hellmann,  Berlin. 


MINUTES    OF    THE    PROCEEDINGS.  XI 

"  English  meteorological  literature  of  the  fifteenth  to  the  seven- 
teenth centuries,"  by  Mr.  G.  J.  Symons,  London. 

.  "  Early  individual  observers  of  the  weather  in  the  United  States," 
by  Mr.  A.  J.  Henry,  Washington,  D.  C. 

"Contributions  to  theoretical  meteorology  in  the  United  States 
during  the  Espy-Kedfield  period  ( 1830-'55),"  by  Prof.  Wm.  M.  Davis, 
Cambridge,  Mass. 

"Contributions  to  theoretical  meteorology  in  the  United  States 
during  the  Loomis-Ferrel  period  (1855-'91,"  by  Prof.  Frank  Waldo, 
Princeton,  N.  J. 

"  A  first  attempt  toward  a  bibliography  of  American  contributions 
to  meteorology,"  by  Mr.  Oliver  L.  Fassig,  Washington,  D.  C. 

The  Congress  was  then  declared  adjourned,  sine  die,  by  the  pre- 
siding officer,  Prof.  F.  H.  Bigelow. 

Papers  presented  to  the  Congress  and  not  especially  referred  to  in 
this  report  were  read  by  title  only. 

Oliver  L.  Fassig,  Secretary. 


TABLE  OF  CONTENTS. 


Page. 

Section  I. — "Weather  services  and  methods. 

1.  Meteorological   stations  and   the  publication  of  results  of    observation. 

Prof.  Dr.  J.  Hann,  Director  Austrian  Meteorological  Service,  Vienna..  1 

2.  The  publication  of  weather  maps  and  bulletins.     Robert  H.  Scott,  Sec- 

retary Royal  Meteorological  Council,  London 6 

3.  Functions  of  State  weather  services.     Maj.  H.  H.   C.   Dunwoody,  U.  S. 

Army,  Assistant  Chief  U.  S.  Weather  Bureau,  Washington,  D.  C 9 

4.  The  predictions  of  droughts  in  India.     W.  L.  Dallas,  Assistant  Meteoro- 

logical Reporter  to  the  Government  of  India,  Calcutta 1.3 

5.  Can  we,  by  automatic  records,  at  three  selected  stations  determine  the 

energy  of  a  flash   of  lightning?     Alexander   McAdie,    M.   A.,  U.  S. 
Weather  Bureau,  Washington,  D.  C 18 

6.  The  utilization  of  cloud  observations  in  local  and  general  weather  pre- 

dictions.    Alexander  McAdie,  M.  A.     Plate  i 21 

7.  An  international  cipher  code  for  correspondence  respecting  the  aurora 

and  related  conditions.     Dr.  M.  A.  Veeder,  Lyons,  N.  Y 26 

8.  The  best  method  of  testing  weather  predictions.     Prof.  Dr.  W,  Koppen, 

Marine  Observatory,  Hamburg 29 

9.  The  present  condition  of  the  weather  service — propositions  for  its  improve- 

ment.    Prof.  Dr.  W.  J.  van  Bebber,  Marine  Observatory,  Hamburg..        34 
Appendices: 

I.  Canadian  service 41 

II.  Danish  service 46 

III.  Norwegian  service 45 

IV.  Russian  service 46 

V.  Austrian  service 48 

VI.  Hungarian  service 49 

VII.  Netherland  service 61 

VIII.  British  service 55 

IX.  Berlin  service 58 

X.  Swiss  service 60 

XI.  United  States  service 62 

Section  II.— Rivers  and  floods. 

1.  Floods  of  the  Mississippi  River,  with  reference  to  the  inundation  of  the 

alluvial  valley.     William  Starling,  Chief  Engineer,  Mississippi  Levee 
Commission,  Greenville,  Miss 68 

2.  Flood  planes  of  the  Mississippi  River.     J.  A.  Ockerson,  U.  S.  Engineer, 

Mississippi  River  Commission,  St.  Louis,  Mo.     Plates  ii-iv 81 

3.  River-stage  predictions  in  the   United  States.     Prof.  Thomas  Russell, 

Office  of  U.  S.  Engineers,  Sault  Ste.  Marie,  Mich 89 

4.  Methods  in  use  in  France  in  forecasting  floods.     M.  Babinet,  Assistant 

Secretary  of  the  Commission  for  Forecasting  Floods,  Paris 94 

5.  The  four  great  rivers  of  Siberia.     Dr.   Franz  Otto  Sperk,  Smolensk, 

Russia 101 

xiii 


Xiv  TABLE    OF    CONTENTS. 

Section  II.— Rivers  and  floods — Continued. 

6.  Regimen  of  the  Rhine  region:  high  water  phenomena  and  their  predic- 

tion.    M.  von  Tein,  Central  Bureau  for  Meteorology  and  Hydrography 

of  Baden,  Karlsruhe 117 

7.  The  Nile.     Mr.  W.  Willcocks,  M.  I.  C  E.,  Director  General  of  the  Res- 

ervoirs of  Egypt,  Cairo.     Plate  v 121 

8.  The  best  means  of  finding  rules  for  predicting  floods  in  water  courses. 

M.  Babinet,  Paris 142 

Section  HI.— Marine  meteorology. 

1.  The  forecasting  of  ocean  storms  and  the  best  method  of  making  such 

forecasts  available  to  commerce.     William  AUingham,  London 150 

2.  The   creation  of  meteorological  observatories   on  islands  connected   by 

cable  with  a  continent.     Albert,  Prince  of  Monaco 168 

3.  The  marine  nephoscope  and  its  usefulness  to  the  navigator.     Prof.  Cleve- 

land Abbe,  U.  S.  Weather  Bureau,  Washington,  D.  C.     Plate  vi 161 

4.  The  barometer  at  sea.     T.  S.  O'Leary,  U.  S.  Hydrographic  OflBce,  Wash- 

ington, D.  C  167 

o.  The  secular  change  in  the  direction  of  the  magnetic  needle;  its  cause  and 
period.  G.  W.  Littlehales,  U.  S.  Hydrographic  Office,  Washington, 
D.  C 174 

6.  Relations  between  the  barometric  pressure  and  the  direction  and  strength  of 

ocean  currents.  Lieut.  W.  H.  Beehler,  U.  S.  Navy,  Chief  of  Division 
of  Meteorology,  U.  S.  Hydrographic  Office,  Washington,  D.  C.  Plate 
VII : 177 

7.  The  periodic  and  non-periodic  fluctuations  in  the  latitude  of  storm  tracks. 

Dr.  M.  A.  Veeder,  Lyons,  N.  Y 185 

8.  North  Atlantic  currents  and  surface  temperatures.     Lieut.  A.  Hautreux, 

French  Navy.     Plates  vni-x 192 

9.  Storms  in  the  South  Atlantic.     Capt.  A.  P.  Pinheiro,  Chief  of  the  Meteor- 

ological Service  of  the  Brazilian  Navy,  Rio  de  Janeiro 204 


LIST   OF  PLATES. 


I^J^IST    I. 


Plate        I.  Relation  between  temperature  and  cloudiness.     McAdie. 

Plate       II.  Location  of  gauges  on  the  Lower  Mississipppi  River.     Ockerson. 

Plate     III.   Highest  annual  stages  of  the  Mississippi  River  and  dates  of  their  occurrence, 

1872-'93.     Ockerson. 
Plate     IV.  Hydrographs  of  the  Mississippi,  the  Missonri,  and  the  Ohio  rivers,  1872-'92. 

Ockerson. 
Plate       V.  The  Nile.     Willcocks. 
Plate     VI.  The  marine  nephoscope.     Abbe. 

Plate    VII.  Barometric  pressure  at  sea  and  ocean  currents.     Beehler. 
Plate  VIIT.  Currents  of  the  Atlantic  in  1892.     Temperatures  of  the  surface  of  the  sea 

in  the  Bay  of  Biscay.     Hautreux. 
Plate     IX.   Drifting  bottles,  June,  1893.     Hautreux. 
Plate       X.  Temperatures  of  the  sea  from  the  Gironde  to  the  La  Plata  River.    Hautreax. 


PAPERS    READ 


BEFORE    THE 


chicaCtO  meteorological  congress. 

.iLTJO-TJST    21-24=,   1893. 


SECTION    I. 

WEATHER    SERVICES    AND    METHODS. 


1.— METEOROLOGICAL   STATIONS   AND  THE   PUBLICATION  OF 
RESULTS  OP  OBSERVATIONS. 

Prof.  Dr.  J.  Hann. 

I. — WHAT  ADDITIONAL  STATIONS  ARE  DESIRED  FOR  METEOROLOGICAL 
AND  FOR  CLIMATOLOGICAL  PURPOSES  ? 

In  many  important  fields  of  meteorology  the  progress  of  our 
knowledge  depends  upon  the  uniform  distribution  of  the  meteoro- 
logical stations  over  the  earth's  surface,  so  that  large  districts  shall 
not  remain  without  observing  stations. 

I  will  only  point  out  that  the  important  question,  whether  the 
mean  temperature  of  the  entire  earth's  surface  as  well  as  the  quan- 
tity of  precipitation,  etc.,  undergoes  periodic  or  continual  changes, 
can  only  be  settled  when  no  great  part  of  it  remains  without  stations. 
Only  then  shall  we  be  certain  that  changes  in  the  mean  condition  of 
the  atmosphere  observed  at  certain  stations  are  not  compensated  for 
in  a  contrary  sense  on  those  parts  of  the  earth  which  lack  stations. 

The  vast  extent  of  the  ocean  will  always  be  a  great  obstacle  to  the 
investigation  of  the  mean  condition  and  variation  of  the  atmosphere 
over  the  whole  earth.  It  is  the  more  important  that  all  oceanic 
islands  should,  if  possible,  have  meteorological  stations,  and  this  is 
especially  true  of  the  islands  of  the  Pacific.  There  should  be  at 
least  uninterrupted  records  of  temperature  and  rainfall.  Much  prog- 
ress latterly  has  been  made  in  this  respect  but  much  remains  to  be 
done.  The  southern  oceans,  unfortunately,  remain  almost  without 
stations.  Still,  by  buried  thermometers  on  the  islands  in  the  South 
Pacific,  Atlantic,  and  Indian  oceans  some  temperature  determinations 
may  be  made,  since  the  determination  of  the  constant  earth  tem- 
perature at  suitable  points  may  be  employed  as  a  substitute  for  the 
estimation  of  the  mean  air  temperature  when  there  is  no  prospect  of 
establishing  permanent  stations. 

In  the  first  place,  I  would  insist  on  the  occupation  of  the  oceanic 
islands  by  meteorological  stations,  since  here  appear  the  great  gaps 


2  CHICAGO    METEOROLOGICAL   CONGRESS. 

in  our  knowledge  of  the  meteorological  conditions  of  the  whole  earth's 
surface. 

Referring  to  certain  portions  of  the  globe,  it  is  very  important  that 
a  ring  of  meteorological  stations  surrounding  the  North  Pole  should 
be  in  constant  operation.  The  Polar  region  north  of  Europe  and 
Asia  is  tolerably  well  surrounded  by  the  meteorological  stations  of 
Russia,  Norway,  and  Denmark,  but  a  permanent  station  on  Nova 
Zembla  is  perhaps  attainable ;  a  similar  station  in  Spitsbergen  re- 
mains perhaps  only  a  hope,  but  it  would  be  of  great  importance  for 
the  determination  of  the  climatological  variation  of  the  European 
frozen  ocean. 

We  have  to  thank  Denmark  for  the  installation  of  meteorological 
stations  on  the  coast  of  west  Greenland  up  to  very  high  latitudes. 
Thence,  further  west,  there  exists  a  deplorable  gap  for  which,  how- 
ever, the  explanation  and  excuse  are  not  far  to  seek.  Nevertheless, 
when  possible,  efforts  should  be  made  to  establish  a  permanent  me- 
teorological station  in  Arctic  North  America  between  60°  and  165° 
west  from  Greenwich,  near  the  seventieth  parallel,  the  further  west 
the  better.  Point  Barrow  would  be  a  suitable  point  for  such  a  per- 
manent station.  Perhaps  this  desideratum  for  science  is  already  a 
reality.  One  or  two  of  the  stations  in  northern  Alaska  should  be  in 
constant  operation.  In  the  Antarctic  latitudes  there  can  be  no 
question  of  permanent  stations.  The  most  southerly  stations  in 
South  America  and  in  New  Zealand  are,  therefore,  very  important  as 
being  those  in  the  highest  latitudes  which  it  is  possible  to  reach  in 
the  southern  hemisphere.  Much  value  consequently  attaches  to  the 
permanency  of  these  stations  and  to  the  regular  publication  of  the 
results  of  the  observations. 

In  the  temperate  latitudes  of  both  hemispheres,  so  far  as  they  are 
not  occupied  by  the  oceans,  a  sufficient  number  of  stations  has  gen- 
erally been  provided,  and  the  existing  gaps  will  no  doubt  shortly  be 
filled.  Matters  are  not  so  favorable  as  regards  the  occupation  of  the 
tropical  zone  by  meteorological  stations. 

The  greatest  gaps  we  find  in  South  America.  In  tropical  South 
America  meteorological  stations  are  almost  completely  lacking,  at 
least  in  the  interior.  Some  stations  in  the  great  Amazon  Valley 
would  be  of  much  importance.  In  Para,  Manaos,  Teffe  (Ega),  Taba- 
tinga,  and  Iquitos,  the  establishment  of  meteorological  stations  would 
present  no  impossibility.  In  the  same  way  stations  could  be  estab- 
lished at  some  of  the  capitals  of  the  interior  Brazilian  states.  It  is 
to  be  regretted  that  neither  in  Quito,  which  possesses  an  astronomical 
observatory,  nor  in  Bogota,  nor  in  Lima,  are  there  meteorological 
stations  which  publish  their  observations.^     In  short,  tropical  South 

'The  new  meteorological  observatory  "Unanue,"  in  Lima,  will  probably  fill  thi^ 
want.  —Editor. 


ADDITIOiN-AL   STATIONS    DESIRED.  6 

America  remains  the  terra  incognita  as  regards  climatological  and 
meteorological  data. 

Even  in  tropical  Africa,  there  is  improvement  in  this  respect, 
notwithstanding  the  fact  that  tropical  South  America  is  occupied  by- 
civilized  states,  which  is  only  true  to  a  limited  extent  of  the  interior 
of  Africa.  If  the  Egyptian  equatorial  province  was  not,  by  the 
shortsighted  and  foreign  policy  of  a  European  power,  given  up  to 
the  Mahdists,  we  should  now  have  continuous  meteorological  data 
from  Lado  and  the  countries  on  the  banks  of  Lake  Victoria.  A 
good  beginning  had  already  been  made  when  barbarity  interfered. 

Stations  in  the  interior  of  the  Congo  States  would  be  very  desirable, 
but  we  must  still  wait  for  them,  as  well  as  for  stations  in  the  British 
and  German  claims  in  equatorial  East  Africa.  There  is,  however, 
every  prospect  that  in  German  East  Africa  meteorological  stations 
will  be  established. 

Australia  is  already  partially  provided  with  stations,  and,  to  all 
appearances,  the  number  will  be  increased. 

For  the  study  of  certain  interesting  questions  as  to  the  daily 
period  of  wind  direction  and  the  daily  period  of  the  barometer, 
stations  would  be  valuable  if  situated  in  the  midst  of  a  large,  even 
plain.  They  should  be  provided  with  self-recording  barometers  and 
anemometers,  and  the  observations  should  be  published  in  extenso; 
a  series  of  five-year  observations  would  only  suffice  to  answer  the 
proposed  questions,  viz.,  daily  period  of  wind  direction  and  ampli- 
tude of  one  diurnal  oscillation  of  the  barometer.  Those  meteoro- 
logical services  possessing  such  stations  are  requested  to  make  the 
fact  known. 

Stations  on  tropical  plateaux,  or  better,  on  high  mountains  in  the 
tropics,  could  contribute  with  advantage  to  the  question  of  the  ex- 
istence of  long  periods  in  the  mean  air  temperature. 

Long  ago,  in  the  "  Zeitschrift  fiir  Meteorologie,"  I  stated  my  opinion 
that  a  lofty  barometric  station  in  the  equatorial  regions  would  give 
the  best  explanation  of  the  temperature  variation  of  the  stratum  of 
air  lying  between  the  station  and  sea  level.  The  observations  of 
pressure  would  give  a  much  better  indication  of  this  than  the  ther- 
mometer itself,  which  gives  only  the  local  temperature  and  is  subject 
to  many^  disturbing  influences. 

The  barometer  on  a  mountain  is,  therefore,  to  be  regarded  as  a  good 
air  thermometer,  or  at  least  a  kind  of  differential  thermometer  when 
the  true  height  of  the  barometer  is  not  known.  It  indicates  the  tem- 
perature of  the  whole  underlying  air  stratum,  or  at  least  the  varia- 
tions. There  must  also  be  a  base  station  whose  horizontal  distance 
from  the  high  station  is  so  small  that  no  considerable  pressure  gradi- 
ent (in  a  horizontal  direction)  can  be  suspected  l^etween  the  two  sta- 
tions during  a  period  of  some  length,  such  as  a  year's  mean. 


4  CHICAGO    METEOROLOGICAL   CONGRESS. 

If  we  designate  by  B  the  height  of  the  barometer  at  the  base  station, 
by  b  that  at  the  high  station,  by  h  the  difference  of  height  between 
them,  by  Tthe  air  temperature  in  absolute  measures  (that  is,  t  -\-  273°), 
by  R  the  known  constant  (for  dry  air  29.3),  the  equation — 

db  =  dB^^  +  ~-^j,.   clt  dh-dB^^=dh' 

is  the  pressure  change  at  the  high  station,  with  the  pressure  variation 
at  the  corresponding  place  on  the  earth  eliminated,  which  is  only  de- 
pendent on  the  temperature  and  vapor  capacity  of  the  air.  The  true 
thermic  pressure  variation  at  the  height  h  is  accordingly,  for  a  sta- 
tion like  Quito  (6  =  548  millimeters,  /?,  =  about  2,850  meters,  «  =  -J 
(27°  +  13.5),  T  being  therefore  293°,  R  29.3), 

d  h'  =  0.62  dtov  dt  =  1.61  d  h' 

If  the  mean  air  temperature  of  the  stratum  between  sea  level  and 
Quito  changes  1°,  the  barometric  level  in  Quito  alters  0.62  millimeters. 
Changes  of  two-tenths  of  a  degree  centigrade  correspond,  therefore,  to 
a  pressure  change  of  something  more  than  0.1  millimeter,  which 
allows  of  accurate  determination  in  the  means  of  the  year. 

If,  for  example,  a  period  corresponding  to  the  sun-spot  period  ex- 
ists in  the  mean  air  temperature,  it  must  also  be  equally  well  shown 
in  the  pressure  variations  of  the  high  station  to  allow  its  magnitude 
to  be  calculated.  While  the  thermometer  only  gives  the  local  air 
temperature  of  Guayaquil  and  Quito,  for  example,  which  is  much 
influenced  by  chance  circumstances,  clouds,  precipitation,  etc.,  the 
barometer  furnishes  the  true  air  temperature  of  the  whole  2,850  meters 
of  air,  as  well  as  the  effect  produced  in  the  same  way  by  changes  in 
the  amount  of  vapor,  that  is  to  say,  in  a  certain  degree  the  "  poten- 
tial "  temperature.  The  mean  barometric  pressures,  therefore,  of  the 
tropical  high  stations  give  much  more  precise  indications  of  the  varia- 
tion of  the  air  temperature,  and  thereby  of  the  solar  radiation,  than 
the  thermometer  itself.  In  order  to  derive  the  full  advantages  of  this 
method  of  measuring  the  air  temperature  by  the  barometer,  the  lower 
station,  where  the  higher  pressure  is  observed,  must  not  be  so  far  re- 
moved from  the  upper  stratum  that  the  relation  dh=-dB  (b  :  B)  holds. 
Quito,  therefore,  would  not  be  a  good  station  for  this  purpose.  A  per- 
manent station  on  the  Dodabetta  Peak,  in  South  India,  on  the  con- 
trary would  be  very  suitable.  If  the  Indian  Government  would  erect 
a  first  class  observatory  on  the  Dodabetta  Peak,  in  the  Nilgiri  Hills, 
science  would  be  much  benefited.  Such  a  station  would  aid  meteor- 
ology greatly  in  other  directions.  Still  better  would  be  a  permanent 
station  on  the  Kamerun  Peak,  in  West  Africa,  but  the  erection  would 
present  much  greater  difficulties  than  that  on  the  Dodabetta  Peak, 
which  could  be  easily  carried  out.  (The  high  station  of  Nuwara 
Eliya,  1,902  meters,  in  Ceylon,  if  only  the  barometer  correction  is 


ADDITIONAL    STATIONS    DESIRED.  O 

sufficiently  constant,  I  would  already  place  in  this  category.)  Even 
if  the  exact  altitude  above  sea  level  of  such  a  tropical  station  is  un- 
known, still,  by  the  introduction  of  an  approximate  value  for  h  in 
the  above  formula,  the  variation  of  the  lower  air  stratum  can  be  cal- 
culated even  if  the  mean  temperature  of  the  whole  air  stratum  cannot. 
The  greatest  importance  is  to  be  attributed  to  the  constancy  of  the 
barometric  correction  or  to  the  accurate  determination  of  any  change 
therein.  Short,  but  entirely  homogeneous,  series  of  pressure  means 
can  be  used  to  determine  the  variations  of  the  mean  air  temperature. 

II. — SHOULD  THE  PUBLICATION  OF  CLIMATIC  DATA  BE  FOR  PLACES 
OR  DISTRICTS  AS  REPRESENTED  BY  PLACES  ? 

Each  observing  system  should  publish,  for  a  certain  number  of 
chosen  stations,  whose  number  corresponds  to  the  size  of  the  country, 
thrice-daily  observations  in  extenso,  and  besides  these,  at  certain  prin- 
cipal stations,  hourly  observations,  as  is  in  fact  done  by  most  of  the 
great  European  systems. 

Besides  these,  for  as  many  stations  as  possil)le,  the  monthly  and 
annual  means  should  be  published  according  to  the  international 
scheme,  as  has  been  done  in  the  last  reports  of  the  Signal  Service. 
Only  in  this  way  can  the  records  of  the  meteorological  stations  be 
made  useful  generally,  and  the  progress  of  the  science  toward  effi- 
ciency be  promoted. 

It  is  to  be  very  much  regretted  that  the  observations  are  not  pub- 
lished for  many  stations,  which,  from  their  positions,  fill  important 
gaps  in  our  climatological  and  meteorological  knowledge,  whereby  all 
the  labor  which  has  been  given  to  making  the  observations  is  ren- 
dered useless. 

In  other  cases  the'  publication  is  in  an  entirely  unsuitable  form,  so 
that  the  results  cannot  be  used  scientifically,  or  they  appear  only  in 
local  papers  which  do  not  reach  the  specialists. 

The  installation  of  stations  and  the  best  equipment  of  them  with 
instruments,  their  care  and  reading,  are  useless,  if  the  results  of  the 
observations  are  not  sufficiently  made  public.  Economy  in  money 
in  the  publication  of  observations  must  be  characterized  as  the 
greatest  prodigality,  since  all  the  outlay  expended  on  the  station  and 
the  care  given  to  reading  the  instruments  are  thus  rendered  useless. 
It  is  to  be  remembered  that  the  worth  of  the  meteorological  data 
may  be  increased  in  a  notable  way,  since  for  data  which  only  go  into 
the  archives,  the  zeal  and  care  diminish.  The  observer  who  sees  his 
observations,  or  important  extracts  thereof,  printed  and  distributed, 
will  always  try  to  make  them  correctly.  Criticism  of  the  observa- 
tions, and  its  beneficial  influence  on  their  value,  will  be  greatly  in- 
creased by  their  publication. 

In  the  most  liberal  form  of  publication  of  observations  in  any 


6  CHICAGO    METEOROLOGICAL   CONGRESS.  '  '^ 

meteorological  system,  as  for  example,  that  of  the  Central  Physical 
Observatory  at  St.  Petersburg,  the  cost  of  printing  forms  only  a  small 
percentage  of  the  cost  of  the  whole  observing  system,  even  when  the 
labor  of  the  observer  is  not  considered.  The  permanent  value  of  the 
activity  of  a  meteorological  system  lies  in  its  annual  reports,  and  on 
these  the  greatest  efforts  should  be  concentrated.  The  annual  reports 
of  the  various  observing  systems  of  the  world  form  the  evidences  which 
seem  destined  to  be  laid  before  future  generations  as  proofs  of  the  pres- 
ent condition  of  the  atmosphere  over  the  earth's  surface  and  for  the 
study  and  progress  of  science.  Therefore,  we  owe  it  to  our  successors  to 
hand  over  to  them  yearly  as  detailed  reports  as  possible  of  the  mete- 
orological occurrences  over  the  entire  globe,  in  order  that  with  the  lapse 
of  time  they  may  be  able  to  answer  the  question  as  to  the  secular 
variation  of  the  meteorological  elements.  It  is  thus  always  better  to 
publish  too  much  than  too  little,  since  what  is  missed  cannot  be 
recovered,  and  avenges  itself  by  retarding  the  progress  of  the  science. 

The  publication  of  meteorological  means  for  whole  districts  has  no 
value  scientifically.  It  can,  perhaps,  for  purely  practical  purposes 
be  used  to  advantage,  but  for  all  scientific  work  such  combined 
means  are  wholly  unserviceable.  It  is  unnecessary  to  insist  on  this, 
for  anyone  who  has  employed  meteorological  means  and  data  in 
general  for  scientific  work  will  agree  with  me.  Neither  the  stations 
of  a  country  nor  of  a  district,  the  instruments  and  their  exposure, 
nor  the  local  influences  at  the  various  stations  remain  constant  long 
enough  to  make  the  means  for  whole  districts  appear  even  tolerably 
comparable. 

The  means  for  districts  from  different  series  of  years  are  not  com- 
parable with  one  another  and  can  not  be  employed  to  show  the 
changes  of  the  meteorological  elements  with  time.  In  general  such 
meteorological  means  and  data  for  whole  districts  should  he  confined 
strictly  within  the  limits  to  which  they  belong.  They  are  only  to  be 
employed  as  rough  approximations,  which,  occasionally,  may  be  very 
useful  practically,  but  are  unserviceable  from  a  scientific  standpoint. 


2.— THE  PUBLICATION  OF   DAILY  WEATHER  MAPS  AND 

BULLETINS. 

Robert  H.  Scott. 

The  subject  which  has  been  placed  before  me  is  one  which  hardly 
admits  of  any  very  decided  treatment,  inasmuch  as  the  scale  and 
character  of  the  maps  to  be  published  in  each  country  must  depend 
firstly  on  the  amount  of  money  which  can  be  appropriated  to  the 
service  of  preparation  and  issue  of  these  maps,  and  secondly  on  the 
extent  of  area  which  the  maps  are  intended  to  cover. 


PUBLICATION   OF    MAPS   AND    BULLETINS.  7 

It  seems  to  me  to  be  out  of  place  and  useless  to  prescribe  for  any 
gentleman,  at  the  head  of  a  meteorological  service,  what  he  ought  to 
publish ;  of  that  he  is  a  far  better  judge  than  any  other  person,  or 
collection  of  persons,  such  as  a  congress  possibly  can  be.  And,  as 
moreover,  no  congress  can  possess  any  executive  power  to  enforce  its 
resolutions,  I  fail  to  see  the  utility  of  proposing  such. 

To  take  a  single  example.  One  of  the  oldest  meteorological  bulle- 
tins in  Europe  is  the  "Bulletin  Meteorologique  du  Nord.''  This 
contains  the  observations  from  Denmark,  Norway,  and  Sweden,  but 
no  maps  of  any  description.  The  congress  can  hardly  go  so  far  as  to 
recommend  the  three  gentlemen  under  whose  direction  this  publica- 
tion appears,  to  change  its  character  and  adopt  the  system,  say,  of 
the  Weather  Bureau  at  Washington.  Is  there  the  slightest  probability 
that  their  respective  governments  would  increase  their  annual  allow- 
ances so  as  to  render  such  a  scheme  practicable?  I  say  nothing  of 
other  offices  whose  bulletins  are  even  less  full  than  that  which  I  have 
cited  as  an  instance. 

I  shall,  therefore,  confine  myself  to  an  account  of  what  the  expe- 
rience of  thirty-two  years  in  the  preparation  of  weather  reports  and 
of  twenty-four  years  in  their  issue  to  the  public  has  shown  this  office 
as  being  well  suited  to  the  requirements  of  the  population  of  the 
British  Islands,  some  two  hundred  copies  being  issued  daily  to  sub- 
scribers, in  addition  to  the  free  issue,  as  described  in  our  annual 
reports. 

The  daily  weather  report. — This  consists  of  a  large  she^t  of  royal 
quarto  size,  which  appears  daily,  and  is  accompanied  monthly  by  a 
sheet  containing  corrections  of  occasional  errors,  and  also  reports 
which  from  any  cause  have  arrived  too  late  for  insertion  in  the  daily 
issue.  The  bound  volume  of  these  reports  for  the  last  six  months  of 
1891  contains  also  tables  of  mean  values  of  the  most  important  ele- 
ments of  the  reports  for  a  period  of  years — in  most  cases  twenty,  but 
in  the  case  of  rainfall  for  twenty-five  years. 

The  information  given  in  the  report  is  that  received  by  telegraph, 
and  it  is  conveyed  by  the  use  of  the  International  Code,  recommended 
for  introduction  by  the  Permanent  Committee  of  the  Vienna  Congress 
at  its  meeting  at  Utrecht  in  1874,  and  finally  adopted  by  the  congress 
of  Rome  at  its  fifth  meeting,  April  22,  1879.  This  code  provides  for 
the  transmission  in  the  morning  telegrams  of  information  sufficient 
for  the  preparation  of  two  maps,  one  for  the  morning  of  the  day  on 
which  the  telegram  is  dispatched  and  one  for  the  previous  evening. 

The  information  conveyed  in  the  telegram  relates  to  pressure,  tem- 
perature, humidity,  wind  direction  and  force,  weather  at  the  epoch  of 
observation,  amount,  if  any,  of  rain,  or  of  snow  (measured  as  water), 
and  condition  of  the  sea  surface.  (It  need  not  be  said  that  the  last 
entry  is  blank  for  inland  and  for  sheltered  stations.) 


8  CHICAGO    METEOROLOGICAL    CONGRESS. 

From  these  observations  there  are  two  charts  prepared  for  8  a.  m., 
one  showing  the  barometer,  wind,  and  sea  disturbance,  (the  wind  by- 
arrows  and  the  sea  disturbance  by  hatching),  the  other  showing  the 
temperature  by  isotherms  at  10°  apart,  and  the  rain  in  figures,  where 
it  exceeds  0.5  inch.  Changes  in  pressure  or  temperature  are  printed 
in  words  across  the  face  of  the  respective  maps. 

The  chart  for  the  previous  evening  is  not  published  by  the  office 
except  in  its  weekly  weather  report,  which  will  be  described  presently, 
but  a  copy  is  supplied  to  "  The  Times  "  newspaper,  and  appears  in  its 
morning  issue  of  the  following  day,  and  so  secures  a  very  extensive 
circulation. 

A  copy  of  the  8  a.  m.  chart  is  also  forwarded  to  "  The  Times,"  and 
incorj)orated  in  the  second  edition,  but  the  circulation  of  that  edition 
is  not  very  extensive. 

Both  of  these  copies  are  prepared  expressly  for  "  The  Times,"  and 
at  the  sole  cost  of  that  journal,  which  for  more  than  thirty  years, 
ever  since  meteorological  telegraphy  was  organized  by  Admiral  Fitz 
Roy  in  1860,  has  been  conspicuous  by  the  prominence  it  has  given  in 
its  columns  to  meteorological  information.  In  fact,  for  some  years, 
the  entire  service  for  the  preparation  of  these  6  p.  m.  charts  was  car- 
ried on  at  the  sole  cost  of  "  The  Times,"  a  fact  which  affords  strong 
evidence  of  the  public  interest  in  weather  intelligence  evinced  in  this 
country. 

The  weekly  iveather  report. — This  was  commenced  in  1878  at  the 
suggestion  of  eminent  agricultural  authorities,  in  order  to  supply  for 
the  different  agricultural  districts  statements  of  the  temperature  and 
amount  of  rain  for  the  week,  and  of  their  differences  from  their 
respective  averages.  In  1884  this  report  was  materially  improved  by 
the  insertion  of  figures  illustrating  the  weekly  march  of  cumulative 
temperature,  that  is,  of  the  number  of  "day  degrees"  of  temperature 
above  or  below  42°  F.  (approximately  6°  C),  which,  according  to  the 
late  Alphonse  de  Candolle,  is  the  degree  of  temperature  at  which 
active  vegetable  growth  may  be  assumed  to  commence.  A  popular 
explanation  of  this  cumulative  temperature  will  be  found  in  a  paper 
read  by  me  before  the  International  Health  Commission  in  1874. 
An  explanation  of  the  scientific  principles  on  which  the  calculation 
of  the  values  published  weekly  is  based  will  be  found  in  a  paper  by 
Lieut.  Gen.  R.  Strachey,  which  appeared  in  the  "Quarterly  Weather 
Report"  for  1878. 

At  the  present  date,  1893,  this  report  contains  on  the  first  page,  for 
each  of  twelve  districts : 

For  temperature. — The  average  and  the  absolute  maximum  and 
minimum.  The  mean  for  the  week,  and  its  difference  from  the  aver- 
age for  the  week. 

For  accumulated  heat. — The  number  of  day  degrees  above  and  be- 


STATE   WEATHER   SERVICES.  9 

low  42°  F.  for  the  week,  and  their  respective  differences  from  the 
mean,  with  similar  information  for  the  interval  elapsed  from  the 
beginning  of  the  current  year  to  the  last  day  in  the  report. 

For  rain. — The  number  of  wet  days.  The  total  fall  for  the  week, 
and  its  difference  from  the  average,  and  similar  information,  as  be- 
fore, for  the  interval  from  the  beginning  of  the  year. 

For  sunshine. — The  number  of  hours  recorded  during  the  week,  its 
percentage  of  the  possible  duration,  and  its  difference  from  the  aver- 
age, with  similar  data  for  the  interval  since  the  commencement  of 
the  year,  and  general  remarks  on  the  weather  for  the  week. 

Page  2  gives  information  for  each  of  the  stations,  as  regards  tem- 
perature, rain,  and  sunshine,  with  differences  from  averages  for  the 
week. 

Then  follow  weather  maps  for  the  whole  of  Europe  as  far  eastward 
as  Odessa,  Moscow,  and  Archangel,  giving,  respectively,  pressure  and 
wind  for  8  a.  m.  and  for  6  p.  m.,  and  temperature  and  weather  for  8 
a.  m.  only. 

Remarks  are  given  for  each  day,  and  the  report  concludes  with  a 
table  of  sunshine  values  for  additional  stations  in  the  United 
Kingdom. 

Appendices  have,  in  successive  years,  appeared  in  connection  with 
the  "Weekly  Weather  Report,"  and  inter  alia  these  have  contained 
figures  giving,  for  each  of  the  districts  into  which  these  islands  have 
been  divided,  the  weekly  and  progressive  values  of  the  different  ele- 
ments for  each  year  as  far  back  as  1879. 

The  daily  and  weekly  weather  reports  are  accompanied  by  monthly 
summaries,  giving,  for  calendar  months,  a  brief  summary  of  the 
weather  over  the  United  Kingdom. 

This  is  a  brief  account  of  the  amount  and  character  of  the  informa- 
tion which  the  experience  of  this  office  has  led  it  to  issue  daily, 
weekly,  and  monthly,  for  the  use  of  the  public. 


3.— FUNCTIONS  OF  STATE  "WEATHER  SERVICES. 
Major  H.  H.  C.  Duxwoody,  U.  S.  A. 

State  Weather  Services  are  organizations  for  the  collection  and 
dissemination  of  climatological  and  other  information.  They  depend 
almost  wholly  upon  the  voluntary  co-operation  of  intelligent  and 
public-spirited  citizens,  whose  individual  reports  collected  at  the  sev- 
eral central  stations  form  the  basis  of  their  publications.  These  pub- 
lications are  reviews  of  the  prevailing  weather  conditions  published 
monthly,  and  bulletins  issued  weekly  during  the  season  of  planting, 
cultivating,  and  harvesting  of  crops,  giving  the  more  important 
weather  features  and  their  effect  upon  growing  crops  from  week  to 


10  CHICAGO    METEOROLOGICAL    CONGRESS. 

week.  Through  State  weather  service  organizations,  the  daily  weather 
forecasts  and  special  warnings  of  the  National  Bureau  are  distributed 
to  large  numbers  of  stations  throughout  the  country. 

There  are  three  independent  lines  of  work,  each  dependent  upon 
its  special  class  of  contributors  who  serve  in  the  capacity  of  (1)  me- 
teorological observers,  taking  observations  of  temperature,  rainfall 
and  miscellaneous  data;  (2)  crop  correspondents,  who,  during  the 
crop  season,  render  weekly  reports  of  farming  operations,  the  growth, 
maturing,  and  harvesting  of  crops,  and  the  effects  of  the  prevailing 
weather  conditions  thereon  ;  (3)  the  forecast  displaymen,  who  display 
flags  or  sound  whistle  signals  representing  the  weather  forecasts  of 
the  National  Weather  Service.  It  not  infrequently  happens  that  one 
person  serves  in  more  than  one  capacity  and  sometimes  co-operates 
in  all  the  three  distinct  lines  of  work. 

In  the  United  States  there  are  less  than  175  meteorological  stations 
conducted  by  the  regular  paid  observers  of  the  Weather  Bureau,  or 
about  one  station  for  each  22,000  square  miles  of  territory.  The 
utter  inadequacy  of  the  data  supplied  by  these  stations  for  pur- 
poses of  detailed  investigation  of  special  localities  is  therefore  plainly 
apparent,  making  the  State  weather  service  an  absolute  necessity 
for  the  prosecution  of  such  work. 

Although  the  work  of  collecting  voluntary  meteorological  observa- 
tions and  publishing  the  results  was  begun  in  Iowa  as  early  as  1875, 
and  in  Missouri  in  1878,  the  organization  of  State  weather  services 
for  the  active  prosecution  of  work  on  the  lines  previously  referred  to 
may  be  said  to  have  begun  in  1881  and  1882,  since  which  time  the 
number  of  meteorological  stations  has  steadily  increased,  there  being 
now  about  3,000  stations  taking  and  recording  meteorological  obser- 
vations daily.  With  this  extensive  system  it  is  possible  to  determine 
the  special  climatic  features  of  every  section  of  the  country  to  an  ^ 
extent  that  would  be  entirely  impossible  were  it  not  for  the  existence 
of  local  weather  services. 

All  State  weather  services  issue  monthly  reviews  of  the  prevailing 
weather  conditions,  and  many  of  these  publications  are  issued  in 
elaborate  and  attractive  form,  rendering  them  valuable  and  interest- 
ing. In  many  of  these  monthly  reviews,  besides  giving  a  general  dis- 
cussion of  the  daily  temperature  and  precipitation,  observations  are 
published  in  detail.  While  it  would  be  difficult  to  correctly  estimate 
the  great  value  of  this  particular  line  of  State  weather  service  work, 
a  more  popular  feature  is  the  weather-crop  service.  From  the  begin- 
ning of  the  crop  season  until  its  close,  weekly  reports  of  the  weather 
conditions  and  the  effects  of  the  same  upon  farming  operations,  the 
growth  of  crops,  etc.,  are  collected  at  the  several  State  weather  service 
centers.  These  weather-crop  reports  are  mailed  by  the  correspondents 
80  as  to  reach  the  central  station  on  Tuesday  morning,  and,  as  far  as 


STATE    WEATHER    SERVICES.  11 

possible,  cover  the  Aveek  ending  with  Monday.  Upon  receipt  they 
are  carefully  summarized  and  a  brief  discussion  of  the  general  con- 
ditions prepared,  which,  with  the  detailed  reports  from  the  several 
correspondents,  forms  the  State  crop  bulletin.  The  official  in  charge 
of  each  State  service  on  Tuesday  morning  sends  a  telegraphic  sum- 
mary of  the  more  important  features  of  the  week  to  the  National 
Weather  Bureau  in  Washington. 

The  entire  territory  of  the  country  being  covered  by  local  services, 
complete  information  as  to  weather  and  crop  conditions  is  had  from 
every  section  of  the  United  States.  These  telegraphic  reports  are 
published  in  full  in  the  National  Weather-Crop  Bulletin,  and,  with 
the  charts  of  temperature  and  precipitation  de^jartures,  form  the 
basis  of  a  general  discussion  of  the  weather  and  crop  conditions  for 
the  whole  country. 

The  charts  of  temperature  and  precipitation  departures  are  pre- 
pared from  the  data  collected  principally  from  U.S.  Weather  Bureau 
stations  and  serve  in  a  general  way  to  show  how  the  temperature  and 
rainfall  of  each  week  compares  with  the  normal  of  the  corresponding 
period. 

This  weather-crop  service  is,  with  the  exception  of  the  general 
weather  forecasts,  the  most  valuable  work  being  done  by  the  National 
Bureau,  and  is  the  most  popular  feature  of  State  weather  service  work, 
being  of  greatest  interest  to  agriculturists,  although  the  bulletins 
are  eagerly  looked  for  by  those  interested  in  other  pursuits.  To  the 
intelligent  farmer  it  affords  a  means  of  supplying  accurate  and  impor- 
tant information  as  to  the  condition  of  crops,  enabling  him  to  form 
reliable  estimates  as  to  supply  and  demand.  In  some  States  the  edi- 
tions of  the  local  weather-crop  bulletin  have  already  grown  to  very 
large  proportions,  and  the  demand  for  the  bulletin  is  constantly 
increasing.  More  than  11,000  coj)ies  of  the  Ohio  weather-crop  bul- 
letin are  printed  and  distributed  weekly.  As  an  illustration  of  the 
importance  of  this  work,  it  may  be  stated  that  a  material  change  in 
the  condition  of  the  cotton  crop  in  the  State  of  Texas  influences  the 
cotton  markets  of  the  world ;  and  it  is  the  work  of  the  State  weather 
service  that  presents  weekly  impartial  and  reliable  information  as  to 
the  actual  weather  and  crop  conditions  prevailing  throughout  each 
season. 

The  publicity  given  the  State  and  National  weather-crop  bulletins 
through  the  press  of  the  country  is  so  extensive  that  an  accurate  esti- 
mate of  the  combined  bulletin  and  newspaper  circulation  would  be 
difficult  of  computation!  The  full  text  of  the  National  bulletin, 
including  the  special  telegraphic  reports  from  the  various  States,  is 
telegraphed  each  week  by  the  press  associations  and  printed  on 
Wednesday  in  the  large  dailies.  The  agricultural  press  make  a 
specialty  of  the  bulletin,  and  some  reproduce  in  their  columns  the 


12  CHICAGO    METEOROLOGICAL   CONGRESS. 

charts  of  precipitation  and  temperature.  The  patent-sheet  papers 
also  find  the  bulletin  an  attractive  item,  and  they  extensively  print 
the  bulletins  of  the  States  covered  by  their  circulation.  The  Missouri 
bulletin  is  printed  in  nearly  one  hundred  patent-sheet  papers  issued 
by  the  Kellogg  and  Western  newspaper  companies. 

The  late  Prof.  George  H.  Cook,  for  several  years  Director  of  the 
New  Jersey  Weather  Service,  in  the  work  of  organizing  the  New  Jer- 
sey service,  summarized  the  importance  of  the  State  service  as  fol- 
lows : 

It  will  be  the  means  of  soon  securing  better  predictions  of  weather  changes  and  storms. 

It  will  bring  the  benefits  of  the  National  Weather  Bureau  of  the  United  States  into 
every  county  participating  in  the  State  local  organization. 

It  will  soon  prepare  the  State  for  a  system  of  storm  signals  displayed  from  railroad 
trains  that  will  be  widely  beneficial  to  agricultural  interests. 

It  will  give  to  every  county  the  Government  standards  for  temperature,  rainfall,  wind 
velocity,  humidity,  etc.,  which  are  sources  of  useful  public  information. 

It  will  put  within  I'each  of  local  agricultural  societies  means  of  accurate  observations 
which,  in  the  course  of  years,  must  be  valuable  to  any  locality  in  the  study  and  adaptation 
of  cereals. 

It  will  bring  the  science  and  methods  of  the  National  Weather  Bureau  within  the 
reach  of  the  high  schools  of  the  State,  offering  teachers  and  pupils  alike  excellent 
opportunity  to  study  a  wide  range  of  the  application  of  science  to  foster  and  protect 
agricultural  industry. 

.  It  will  lead  to  the  collection  of  rainfall  statistics  to  enable  engineers  to  better  estimate 
the  supply  of  canals,  also  the  sudden  downpours  to  guard  against  in  laying  out  sewers 
in  cities.  It  will  lead  to  a  correct  knowledge  of  rainfall  over  the  different  watersheds  of 
the  State,  for  the  purpose  of  giving  data  for  supplying  the  water  works  of  cities,  towns, 
and  villages. 

It  will  lead  to  the  forming  of  reliable  meteorological  records  for  use  in  legal  cases. 

It  will  lead  to  publishing  the  temperature  of  summer  resorts,  drawing  attention  of  out- 
side parties  to  their  dasirability  as  summer  residence. 

It  will  lead  to  a  better  practice  of  medicine,  when  physicians  throughout  the  State 
can  study  disease  with  reliable  and  accurate  meteorological  facts  by  their  side — and  for 
sanitary  purposes  correct  meteorological  statistics  are  invaluable  to  the  practitioner  in 
applying  preventive  remedies  for  the  public  good. 

The  growth  and  popularity  of  these  services  were  such  that  in 
November,  1885,  Gen.  W.  B.  Hazen,  Chief  Signal  Officer,  invited  the 
directors  of  all  State  weather  services  to  assemble  in  Washington  for 
the  purpose  of  mutual  conference  and  discussion.  Arrangements 
were  accordingly  made  for  a  convention  of  the  directors,  which  met 
February  24  and  25,  1886.  At  this  conference  many  important  sub- 
jects bearing  upon  State  services  were  discussed  looking  to  improved 
methods  of  taking  and  recording  observations,  and  a  general  inter- 
change of  views  regarding  State  service  work  was  had.  Much  good 
resulted  from  this  conference,  and  a  report  of  its  proceedings  was 
published  with  the  Annual  Report  of  the  Chief  Signal  Officer. 

A  second  and  more  largely  attended  convention  met  in  Rochester 
in  August,  1892,  at  which  the  "  American  Association  of  State 
Weather  Services  "  was  formed,  the  constitution  of  which  provides 


DROUGHTS    IN    INDIA.  13 

for  annual  meetings,  and  the  convention  of  1893  will  be  held  in 
Chicago  in  August  during  the  time  of  the  meeting  of  the  Meteoro- 
logical Congress,  August  21-24. 

During  the  past  year  there  have  been  prepared  by  many  State 
weather  services,  for  exhibit  at  the  World's  Fair,  valuable  and  inter- 
esting charts  illustrating  graphically  the  special  climatic  features  of 
the  several  States.  Some  of  these  exhibits  have  been  prepared  at 
much  expense  of  labor  and  considerable  pecuniary  cost,  and  have 
been  very  favorably  commented  upon. 


4.— THE  PREDICTION  OF  DROUGHTS  IN  INDIA. 
W.  L.  Dallas. 

The  following  gives  an  account  of  the  method  employed  in  India 
for  the  preparation  of  the  seasonal  forecasts  issued  by  the  India 
Meteorological  Department,  the  chief  object  of  which  is  to  give 
warning  of  the  probable  occurrence  of  severe  drought  in  any  large 
area  in  India. 

In  northern  India  there  are  two  distinct  periods  of  rainfall  of 
importance  for  agricultural  operations.  The  first  is  the  period  of 
the  southwest  monsoon  rains  from  June  to  October.  They  are 
heaviest  in  the  coast  districts  and  at  the  foot  of  the  Himalayas,  and 
are  most  intermittent  and  irregular  in  the  more  interior  districts  of 
northern  India.  The  second  period  is  that  of  the  cold  weather  rains 
from  December  to  March,  when  light  to  moderate  showers  are 
received  during  the  passage  of  feeble  cyclonic  storms  across  northern 
India. 

The  chief  causes  of  failure  of  crops  in  northern  India  are : 

1st.  Deficiency  of  rainfall,  more  especially  in  the  southwest  mon- 
soon period. 

2d.  Early  termination  of  the  southwest  moilsoon  rains. 

Under  these  circumstances  the  great  rice  crop  in  the  parts  of  north- 
eastern India  affected  withers  away  and  is  a  more  or  less  complete 
failure.  In  northwestern  India  it  prevents  the  cold  weather  crops 
being  sown,  except  in  low-lying  or  irrigated  districts. 

In  southern  India,  the  Deccan,  and  Burmah,  the  only  period  of 
regular  rains  of  value  for  the  crops  is  that  of  the  southwest  mon- 
soon from  May  to  November  or  December.  In  the  Deccan  and 
southern  India  it  is  moderate  in  May  and  June,  light  from  July  to 
September,  and  moderate  to  very  heavy  in  October,  November,  and 
December, 

In  these  districts  the  rains  may  fail  more  or  less  completely  during 
a  part  or  whole  of  the  period.  The  most  serious  partial  failure  is 
when  the  rainfall  of  the  second  maximum  (October  to  December)  is 
light  and  irregular. 


14  CHICAGO    METEOROLOGICAL   CONGRESS. 

Hence,  in  northern  India  the  most  serious  droughts  are  due  to 
the  combination  of  a  more  or  less  complete  failure  of  the  southwest 
monsoon  rains  followed  by  a  failure  of  the  cold  weather  rains.  In 
this  case  both  crops,  the  kharif  and  rabi,  fail. 

In  southern  India  failure  of  the  crops  and  consequent  famine  is 
due  to  a  more  or  less  serious  and  large  failure  of  the  rains  of  a  com- 
plete southwest  monsoon  period.  The  intensity  of  the  scarcity  or 
famine  consequent  on  the  failure  of  the  crops  under  either  of  these 
conditions  depends  largely  upon  the  character  of  the  previous 
seasons.  If  the  preceding  two  or  three  seasons  have  been  unsatis- 
factory, so  that  the  accumulated  food  stocks  have  been  depleted,  the 
famine  may  be  of  the  most  intense  character. 

The  preceding  remarks  have  shown  that  the  most  important  factor 
in  determining  the  character  of  the  crops  is  the  rainfall  of  the  south- 
west monsoon,  and  hence  long  period  forecasts  in  India  have  been 
chiefly  confined  to  the  prevision  of  the  southwest  monsoon  distribu- 
tion of  rainfall. 

These  forecasts  are  usually  issued  in  the  first  week  of  June,  and 
attempt  to  give  a  rough  estimate  of  the  general  character  of  the  rain- 
fall of  the  next  four  months  in  the  larger  provinces  of  India,  and 
more  especially  to  indicate  any  area  in  which  there  is  a  strong  proba- 
bility the  rainfall  will  be  seriously  below  the  normal,  or  to  point  out 
when  there  is  a  probability  of  unusual  delay  in  the  commencement  of 
the  rains  or  of  their  abnormally  early  termination  in  northern  or 
central  India. 

Rainfall  in  Europe  occurs  chiefly  during  the  passage  of  cyclonic 
storms,  and  hence  is  apparently  fortuitous  in  its  occurrence. 

In  India  at  least  four-fifths  of  the  rainfall  occurs  as  a  normal 
feature  of  the  southwest  monsoon  circulation.  The  lower  air  currents 
of  that  circulation  advance  into  India  from  the  adjacent  sea  areas, 
determined  by  the  regular  periodic  pressure  and  temperature  changes 
in  India  and  central  Asia.  The  circulation  is  mainly  maintained 
and  continued  by  its  internal  energy,  or  rather  by  that  of  the  energy 
set  free  on  the  condensation  of  the  aqueous  vapor  brought  up  in  it 
over  India.  It  varies  to  some  slight  degree  in  intensity  from  year  to 
year,  and  its  extension  also  varies  in  different  years,  dependent  upon 
the  antecedent  meteorological  conditions. 

It  is  this  fact,  that  the  rainfall  of  this  period  is  due  to  the  preva- 
lence of  a  massive  and  steady  current,  and  not  to  local  cyclonic  dis- 
turbances in  a  region  of  irregular  winds,  that  makes  it  probable  long 
prevision  can  be  successfully  attempted  and  carried  out  in  India. 

In  order  that  the  attempt  to  forecast  the  character  and  distribution 
of  the  monsoon  rainfall  from  the  meteorological  conditions  prevail- 
ing anterior  to  the  advance  of  the  rain  giving  southwest  monsoon 


DROUGHTS    IN    INDIA. 


16 


currents,  it  is  essential  that  there  should  be  uniform  and  direct  rela- 
tions between  the  former  as  results  and  the  latter  as  conditions. 

It  is  immaterial  for  the  purposes  of  forecasting,  whether  they  are 
based  upon  experience  or  upon  theory.  It  is  most  satisfactory,  of 
course,  that  relations  emperically  obtained  should  be  proved  to  be  in 
strict  accordance  with  a  rational  theory. 

The  following  gives  a  statement  of  some  of  the  more  important 
uniformities  or  relations  utilized  in  preparing  the  long  period  fore- 
casts in  India : 

A  most  important  feature  is  that  the  general  character  of  the  dis- 
tribution of  the  rainfall  during  the  southwest  monsoon  is  fairly  con- 
stant during  the  whole  period,  and  hence  that  an  area  of  largely  defi- 
cient rainfall  has  usually  deficient  rainfall  throughout  the  whole 
season.  Similarly  for  excessive  rainfall.  The  annual  reports  of  the 
meteorology  of  India  give  numerous  examples  of  the  persistency  of 
the  seasonal  characteristics  throughout  the  whole  monsoon  period. 
It  will  suffice  to  give  one  example.  The  southwest  monsoon  of  1890 
gave  abundant  rain  to  northern  and  central  India  and  the  north 
Deccan,  and  as  usually  happens  when  the  humid  currents  are  more 
largely  determined  to  northern  India  than  usual,  the  rainfall  of  the 
same  season  was  in  defect  in  Burmah  and  southern  India.  The  fol- 
lowing gives  data : 

Percentage  variation  of  rainfall  from  normal. 


District. 


Areas  of  excessive  rainfall: 

Orissa 

Assam  and  east  Bengal 

Lower  Bengal 

Bihar 

Northwestern  Provinces  and  Oudh 

Punjab 

Central  Provinces 

Hyderabad 

Konkan 

Areas  of  decreased  rainfall: 

Mysore 

Carnatic 

Arakan  

Pegu 

Tenasserim 

Upper  Burmah 


1890. 


June.      July.      Aug. 


Sept. 


Total 

for 
period. 


+  33 
4-  28 

4-  22 

+  66 

-j-IIO 

+  33 

+  43 
-f-  20 


—  19 

—  15 

—  19 

—  16 

—  6 

—  41 


tlolt 


+  10 

+  65 

+  45 

4-  28 
+  9 

4- 10  I 

4-  27  i 


—  12 

—  2 

4-24 
+  10 

—  9 

—  39 


+  31 

—  8 

4-  35 

—  3 

—  I 

—  27 

—  20 

—  10 

—  27 

—  30 


4- 

16 

— 

35 

0 

— 

10 

4- 

14 

— 

73 

.. 

24 
1.5 

— 

37 

— 

4 

— 

49 

— 

24 

— 

21 

0 

— 

17 

4-  II 

¥ 

4-  34 
+  28 
4-  15 

nil. 
6 


X 


Hence,  the  steady  tendency  to  increased  rainfall  in  the  former  areas 
was  as  strongly  marked  as  the  large  deficiency  in  the  latter  areas 
throughout  the  whole  season. 

The  above  example  is  very  interesting  on  one  account,  as  it  shows 
persistent  opposite  tendencies  and  variations  in  areas  of  which  the 
meteorological  relations  to  the  monsoon  currents  are  more  or  less 
opposed  or  inverse  to  each  other. 

The  persistent  variations  in  the  distribution  of  the  monsoon  rain- 


16 


CHICAGO    METEOROLOGICAL    CONGRESS. 


fall  are  related  to  persistent  variations  in  the  strength  and  extension 
and  other  characteristics  of  the  great  currents  of  the  period.  It  will 
suffice  to  give  one  case.  The  monsoon  rainfall  was  very  largely  in 
excess  in  Burmah  in  1891.  The  following  table  gives  the  deflection  of 
the  mean  winds  at  three  representative  stations  in  that  area  during 
each  month  of  the  season  : 

Westerly  deflection,  1891. 


station. 

June. 

July. 

Aug. 

Sept. 

Port  Blair                  

o 
+  25 
-j-  25 

4-  20 

o 

+  15 
+    8 

+  28 

0 

+  i8 
+    3 

+  12 

0 
+  25 

+  29 

+  36 

The  winds  at  these  stations  during  the  southwest  monsoon  are 
from  directions  between  south  and  west,  and  increased  westing 
ardently  indicates  a  greater  determination  of  the  Bay  monsoon  cur- 
rent to  Burmah  and  Tenasserim  than  usual. 

Again,  the  monsoon  currents  were  both  stronger  than  usual  in  1892 
during  the  period  July  to  September.  The  following  data  will  show 
that  the  increased  strength  was  marked  throughout  the  whole  of  the 
period,  more  especially  in  the  case  of  the  strongest  current  in  that 
year,  viz.,  the  Bengal  current : 

Percentage  variation  of  strength. 


Name  of  current. 


Bengal  . . 
Bombay . 


June. 


+  30 
—  30 


July. 


+  27 
+    7 


Aug.       Sept. 


+  15 
+  10 


+  32 

+  15 


The  relations  of  the  variations  of  the  strength  and  direction  of  the 
lower  air  currents  during  the  southwest  monsoon  to  the  rainfall  vari- 
ations require  further  investigation,  but  sufficient  data  have  already 
been  accumulated  to  establish  that  there  are  marked  differences  in 
the  strength  and  extension  of  the  monsoon  currents  and  in  the  dis- 
tribution of  the  rainfall  from  year  to  year,  and  that  these  are  directly 
related  to  each  other. 

These  relations  might  have  been  inferred  from  the  fact  that  the 
monsoon  rainfall  is  not  due  to  the  passage  of  cyclonic  storms,  but  to 
the  continued  prevalence  of  a  steady,  strong  current  charged  with  vast 
supplies  of  aqueous  vapor.  Assuming  that  the  character  of  the  dis- 
tribution of  the  rainfall  is  fairly  persistent  throughout  each  season, 
and  that  the  rainfall  is  due  to  the  advance  and  prevalence  of  a 
strong  sea  current  into  the  Indian  land  area,  it  is  evident  that  the 
extension  of  this  current  will  be  to  some  degree  deteiwnined  by  any 
abnormal  meteorological  conditions  present  before  or  during  its 
advance.  The  following  gives  a  brief  statement  of  some  of  these 
determining  conditions : 


DROUGHTS    IN    INDIA.  17 

(1)  Unusually  heavy  and  prolonged  snowfall  in  the  Himalayan 
Mountain  area  has  been  shown  by  Mr.  Blanford  to  exercise  a  very 
powerful  influence.  It  modifies  the  pressure  and  temperature  con- 
ditions in  Qorthern  India,  and  usually  not  only  retards  the  com- 
mencement of  the  monsoon  but  modifies  its  intensity.  The  manner 
in  which  snowfall  modifies  the  hot  weather  conditions  and  the  sub- 
sequent rains  has  been  investigated  and  is  fairly  well  known.  Ab- 
normally deficient  snowfall  and  its  usual  correlative,  more  intense 
hot  weather  conditions  than  usual,  on  the  other  hand  are  found  to 
precede  almost  invariably  stronger  and  steadier  monsoon  than  usual. 

(2)  The  abnormal  pressure  conditions  established  during  the  hot 
weather,  more  especially  if  they  are  marked,  exercise  a  large  influ- 
ence in  modifying  the  set  of  the  monsoon  currents.  The  general 
rule  in  India  is  that  the  hot  weather  tends  to  exaggerate  and  develop 
local  pecularities  of  pressure,  and  the  rains  to  smooth  them  away. 
Thus,  if  the  hot  weather  develop  a  local  deficiency  of  pressure  in  any 
area  it  tends  to  become  a  sink  to  which  the  monsoon  current  is  more 
largely  directed  than  usual,  and  hence  also  affects  the  rainfall  in 
neighboring  districts.  If,  on  the  other  hand,  a  local  excess  of  pres- 
sure is  formed,  as  occasionally  happens  in  Guzerat,  northwest  Rajpu- 
tana,  etc.,  it  usually  accompanies  a  considerable  or  large  diminution 
of  the  rainfall  in  Rajputana  or  northwestern  India.  Much  remains 
to  be  done  to  work  out  fully  the  influence  exerted  by  high  and  low 
abnormal  pressure  areas  in  modifying  the  distribution  of  the  mon- 
soon rainfall,  but  several  useful  relations  have  been  established  and 
are  used  in  drawing  up  these  long-period  forecasts. 

Similarly,  the  consideration  of  the  temperature  conditions  of  India 
during  the  hot  weather  throws  light  on  the  causes  of  the  general  and 
local  pressure  conditions  obtaining  before  the  setting  in  of  the  mon- 
soon, and  hence  enables  their  probable  importance  to  be  estimated. 

An  important  point  to  be  taken  into  consideration  is  the  relative 
strength  of  the  two  currents,  as  upon  this  depends  largely  the  posi- 
tion of  the  monsoon  trough  of  low  pressure,  and  hence  also  the  mean 
tracks  of  the  cyclonic  storms  of  the  rains  and  of  the  heavy  rainfall 
that  accompanies  these  storms.  A  strong  Bombay  monsoon  tends  to 
displace  it  northward  and  a  strong  Bengal  monsoon  southward. 

Another  important  point  is  based  on  the  results  of  Mr.  Blanford's 
investigations  (given  in  the  "Rainfall  of  India")  of  the  relations 
between  the  rainfall  variations  in  different  parts  of  India.  He  has 
worked  out  very  fully  the  areas  in  which  the  rainfall  variations  are 
usually  similar  or  opposite  in  character,  and  the  measure  of  the  prob- 
ability of  similar  or  opposite  variations  occurring  for  any  given  year. 

The  previous  gives  a  few  of   the  more  important  principles  and 
facts  upon  which  the  forecasts  of  the  distribution  of  the  monsoon 
rainfall  are  based, 
2 


18  CHICAGO    METEOROLOGICAL   CONGRESS. 

A  consideration  of  the  snowfall  data  of  the  cold  weather,  of  the 
meteorological  conditions  prevailing  during  the  hot  weather,  and 
more  especially  the  character  and  persistency  of  the  pressure  varia- 
tions, usually  enables  a  rough  estimate  of  the  general  strength  of  the 
monsoon  currents  and  the  distribution  of  the  rainfall  to  be  made. 
This  is  first  done  and  afterwards  a  comparison  is  made  with  previous 
years  in  which  similar  conditions  are  known  to  have  obtained.  By 
taking  into  consideration  the  actual  conditions,  the  relations  estab- 
lished by  Mr.  Blanford  between  the  rainfall  variations  in  different 
areas,  and  the  rainfall  distribution  of  previous  years  of  similar  me- 
teorological conditions,  not  only  the  probable  character  of  the  rain- 
fall can  be  estimated,  but  also  the  probability  of  the  occurrence  of 
deficiency  or  excess  of  rainfall  in  any  area  as  dependent  upon  or 
resulting  from  these  conditions.  This  is  what  is  now  attempted  to 
be  done  in  the  forecasts  issued  annually  in  June  by  the  department, 
and  which  have  had  a  fair  measure  of  success.  For  example,  a  full 
warning  was  given  in  June,  1891,  of  the  drought  in  Rajputana  dur- 
ing the  monsoon  rains  of  that  year. 

It  is  hardly  necessary  to  point  out  that  the  methods  employed  and 
sketched  above  are  practically  identical  with  those  employed  in  giv- 
ing warning  of  the  approach  of  storms,  and  I  may  again  point  out 
that  these  long-period  forecasts  in  India  are  rendered  possible  by  the 
peculiar  features  of  the  southwest  monsoon  air  motion  over  India, 
and  by  the  remarkable  persistency  of  many  of  the  abnormal  condi- 
tions of  the  meteorology  of  that  current. 


5.— CAN  WE  BY  AUTOMATIC  RECORDS  AT  THREE  SELECTED 
STATIONS  DETERMINE  THE  ENERGY  OF  A  FLASH  OF  LIG-HT- 
NING? 

Alexander  McAdie,  M.  A. 

I  may  begin  this  paper  with  an  answer  in  the  affirmative.  It  would 
be  a  good  plan  to  have  these  observations  made.  The  lightning  flash 
has  been  regarded  up  to  the  present  time  as  a  thing  accomplished,  a 
discharge  between  the  electrified  cloud  and  the  earth,  over  about  as 
soon  as  seen.  It  must  be  a  discharge  of  very  high  potential  because 
of  the  length  of  the  spark ;  and  the  potential  being  great  the  capacity 
may  be  small,  if,  as  we  have  some  reason  to  suppose,  the  quantity  of 
electricity  in  a  flash  is  not  great.     CV=z  Q. 

To-day  we  are  beginning  to  look  at  a  lightning  flash  from  a  differ- 
ent point  of  view.  We  study  the  strain  in  the  dielectric,  where  pre- 
viously we  thought  only  of  the  surface  electrification ;  and  the  char- 
acter of  the  discharge  is  now  of  great  importance,  and  where  before 
we  talked  of  forked,  zigzag,  and  sheet  lightning,  a  classification  some- 
what like  Luke  Howard's  cloud  classification,  we  talk  now  of  "ini^ 


ENERGY    OF    A    LIGHTNING    FLASH.  19 

pulsive  rush"  discharges,  meandering  flashes,  etc.  What  we  need, 
and  we  have  in  part,  is  a  systematic  classification  of  the  electri- 
cal discharges  in  the  atmosphere.  At  one  end  of  the  list  we  might 
place  the  impulsive  rush  discharge,  a  most  intense  flash,  and  at 
the  other  the  gentle  glow  discharge  which  we  find  so  frequently  on 
Pikes  Peak  and  Ben  Nevis,  and  now  definitely  connect  with  certain 
meteorological  conditions.  Observe,  too,  that  the  conditions  for  the 
protection  of  life  and  property  are  very  different  for  these  different 
types  of  discharge.  Points  fail  to  be  effective  under  the  impulsive 
rush,  while  most  effective  with  the  glow. 

We  want,  then,  to  classify  our  flashes ;  and  to  get  more  accurately 
at  the  character  of  the  flash,  perhaps  we  should  attempt  to  get  at  the 
energy  of  each  particular  flash.  Dr.  Lodge,  in  his  book  on  "Light- 
ning Rods,"  in  Chapter  xv,  gives  the  suggestion  of  the  editor  of  the 
"  Electrician  "  that,  where  thunderstorms  are  frequent  and  violent, 
it  might  be  possible  to  set  up  lightning  conductors  for  experimental 
purposes,  and  thus  accumulate  experience  concerning  their  behavior 
more  rapidly  than  at  present.  On  a  preceding  page  it  is  also  noted 
how  much  work  could  be  done  at  meteorological  stations  and  obser- 
vatories "  in  the  matter  of  accurately  observing  and  recording  light- 
ning, photographic  records,  obtained  by  proper  appliances  for  distin- 
guishing multiple  from  successive  flashes,  being,  of  course,  superior 
to  all  others.  An  experimental  lightning  conductor  on  a  flagstaff 
near  every  meteorological  observatory  would  also  be  a  most  desirable 
addition.  It  need  not  be  associated  with  danger.  A  system  of  fuses 
or  cut-outs,  or  an  east  or  west  steel  bar,  might  be  used  to  record  the 
passage  of  a  flash,  and  the  rod  need  not  be  examined  until  after  the 
cessation  of  violent  disturbances.  By  having  the  conductor  of  dif- 
ferent thickness  at  different  parts  one  could  learn  what  size  is  really 
likely  to  be  melted.  One  could  also  arrange  so  as  to  gain  informa- 
tion about  side  flashes."  In  the  "  Philosophical  Magazine,"  August, 
1888,  Dr.  Lodge  applies  the  mathematical  expressions  for  the  real 
resistance  and  inductance  of  a  conductor  under  an  alternating  cur- 
rent to  the  case  of  a  lightning  flash.  "An  air-condenser  with  plates 
of  any  size  separated  by  a  distance  /)  (height  of  cloud)  and  charged 
up  to  bursting  strain  (^  gramme  weight  per  square  centimeter;  the 
less  strength  of  rare  air  is  hardly  worth  bothering  about).  Let  a 
small  portion  of  this  condenser,  of  area  -6^,  now  discharge  itself, 
being  separated  from  the  rest  after  the  trap-door  and  guard-ring 
manner.     A  volume  of  dielectric  T^h'h  is  relieved  of  strain,  and  the 

981 
energy  of  the  spark  is  Ez=-^  T^Vh  ergs. 

The  capacity  discharged  is  5=  -j-^--,  and  the  maximum  potential 
can  be  put  at  110 /i  electrostatic  units."     He  then  calculates  the 


20  CHICAGO    METEOROLOGICAL   CONGRESS. 

inductance  of  the  circuit  L  =  h  (fJ^u^-{- 1\),  where  u  may  be  a  number 
not  very  different  from  4  or  5,  and  now  knowing  S  and  L  proceeds 
to  find  the  criterion  for  the  discharge  to  be  oscillatory  and  to  deter- 
mine the  rate  of  alternation.  "  The  discharge  will  be  oscillatory  unless 
the  resistance  it  meets  with  exceeds  a  certain  critical  value,  viz. : 

P  _     ITL  ___     /4  h  p.  u" _  4:hfj.u  _4hu;jLV 


<=^'^=4 


s  ~\  Kb'  ~h\n^ 

1  .  30 

where  v=z    ,  -, — ^^^  •=.  the  velocity  of  light  =:  — 

w{iJ.K)  ^  ^  II 

80  the  critical  resistance  is 

ims. 


^0=120^^/(2  log^-l)ohi 


Suppose  /i  to  be  a  mile  (1,609  meters),  h  50  meters,  and  a  a  milli- 
meter; the  critical  resistance  comes  out  about  15,000  ohms.  When 
the  resistance  then  falls  below  this  the  discharge  will  be  oscillatory. 
The  impedance  to  a  condenser  discharge  comes  out 

impedance  =  60  ,  -i/(  2  log     —  1  )  ohms. 

Or,  it  is  half  the  critical  resistance ;  it  depends  almost  entirely  upon 
the  amount  of  space  magnetized  round  it ;  and  upon  the  capacity  of 
the  discharging  condenser.  Magnetic  permeability,  specific  resist- 
ance, or  even  the  thickness  of  the  conductor,  hardly  matter.  The 
length  of  the  conductor  does  figure. 

Now,  while  we  may  not  erect  a  conductor  a  mile  high,  it  is  feasible 

by  kites,  balloons,  or  aeroplanes  to  carry  up  a  wire  a  millimeter 

thick  some  200   meters.      The  critical   resistance  would   come   out 

something  like  2,000  ohms  and  the  impedance  one-half  of  this,  and 

the  frequency  constant,  n  L=.  impedance,  something  like  3,000,000. 

Now,  the  total  maximum  energy  "  of  a  given  area  of  cloud  is  easily 

estimated,"  says  Lodge,  "  by  remembering  that  as  soon  as  the  electric 

tension  of  the  air  reaches  the  limit  of  about  one-half  gramme  weight 

per  square  centimeter  disruption  occurs ;  and  the  energy  of  the  dielec- 

981 
trie  per  cubic  centimeter  being  —^  ergs,  per  cubic  mile  it  would  be 

4.110  X  10"    , 

2  X  3  X  10''  tons,  equal  to  70,000.000  foot  tons.     The  energy  of 

any  ordinary  flash  can  be  accounted  for  by  the  discharge  of  a  very 
small  portion  of  charged  cloud,  for  an  area  of  10  yards  square  at  a 
height  of  a  mile  would  give  a  discharge  of  over  2,000  foot  tons  of 
energy."  And  for  the  case  we  have  taken,  some  200  meters,  we  should 
have  from  200  to  300  foot  tons,  or  very  roughly  in  the  neighborhood 
of  1,000  horse  power. 

With  three  stations  grouped  then  around  a  common  center,  pro- 
vided with  cameras  with  some  type  of  electrometer  and  with  meteoro- 


CLOUDS    AND    WEATHER    PREDICTION.  21 

logical  apparatus,  we  might  get  first  the  exact  times  of  occurrence  of 
all  visible  discharges ;  and  the  exact  appearance  of  the  flashes,  i.  e., 
not  as  referred  to  one  plane  which  a  single  camera  would  give,  but  the 
character  and  direction  of  the  flash  in  space.  Many  flashes  starting 
from  a  given  point  undoubtedly  meander,  turn  and  twist  upon  them- 
selves, and  some  of  the  seeming  thickenings  in  single  photographs 
are  doubtless  points  simply  of  change  of  direction  of  flash.  Next  we 
would  get  from  the  potential  fluctuations,  as  shown  on  the  electrometer 
records,  the  exact  times  and  something  of  the  individual  strains,  and,  as 
I  have  elsewhere  shown,  evidences  of  discharges  not  visible,  and  in  this 
way  could,  from  a  composite  of  the  records  of  our  three  stations,  get 
at  a  very  good  approximation  of  the  strains  to  which  our  dielectric, 
the  air  between  the  thundercloud  and  ground,  had  been  subjected ; 
and  like  a  piece  of  plate  armor,  when  the  firing  is  over,  we  could 
examine  and  locate  the  places  and  times  of  rupture. 


6.— THE  UTILIZATION  OF  CLOUD  OBSERVATIONS  IN  LOCAL 
AND    G-ENERAL    WEATHER    PREDICTIONS. 

Alexander  McAdie,  M.  A. 

In  our  daily  work  of  forecasting  weather  changes,  we  have  reached 
the  point  where  we  feel  the  necessity  of  some  knowledge  of  the  con- 
ditions of  the  upper  air  strata.  We  map  with  great  success  the  condi- 
tions of  the  bottom  of  the  aerial  ocean  in  which  we  live.  By  the  aid 
of  the  telegraph  we  make  invaluable  synoptic  charts.  We  have  ex- 
cellent ground  plans  or  horizontal  sections,  but  we  attempt  nothing 
in  the  way  of  vertical  sections  of  the  atmosphere.  The  telegraph  is 
not  available ;  some  other  agency  must  be  sought  for.  We,  in  part, 
att'empt  the  exploration  of  the  free  air  by  balloons  and  by  mountain 
observatories,  and  when  aerial  navigation  is  an  accomplished  fact  we 
shall  doubtless  have  systematic  and  extensive  surveys  of  the  atmos- 
phere. But  until  that  happy  time  arrives,  clouds  must  remain  the 
best  exponents  of  conditions  prevailing  at  different  levels  in  the 
atmosphere.  They  can  be  made  to  give  us  even  now,  with  most  crude 
methods,  information  concerning  the  currents  at  different  heights, 
and  indirectly,  temperature  and  moisture  conditions.  Studied  closely 
and  in  connection  with  the  surface  isobars,  isotherms,  and  winds,  the 
forecaster  will  find  in  cloud  motions  and  formations  portions  of  the 
storm  mechanism  otherwise  hidden  from  him.  For  special  as  well 
as  general  forecasting  cloud  study  is  important,  and  I  desire  to  em- 
phasize the  need  of  cloud  study  at  places  along  the  coast.  I  think 
that  if  we  had  well  equipped  stations  at  Capes  Fear,  Lookout,  and 
Hatteras,  with  cloud  conditions  a  subject  of  special  attention,  we 
would  receive  timely  warning  of  the  occasional  storms  that  slip  in 
upon  us  from  the  seaboard. 


22  CHICAGO    METEOROLOGICAL    CONGRESS. 

Cloud  nomenclature  and  the  various  methods  of  cloud  measure- 
ment do  not  fall  strictly  within  the  limits  of  this  paper.  Both  topics 
require  special  papers.  But  for  the  purposes  of  general  forecasting 
we  need,  first,  a  codification  of  what  for  want  of  a  name  I  shall  call 
"cloud  laws",  i.  e.,  the  results  of  studies  of  cloud  formation  and 
movement;  and  secondly,  some  cipher  scheme  at  once  flexible  and 
definite  that  will  convey  to  a  distance  the  actual  aspect  of  the  sky. 

Hildebrandsson  in  his  paper  (read  before  the  Royal  Meteorological 
Society,  London,  February  16,  1887)  divides  the  problem  into  two 
sections — how  to  best  study  the  relation  of  formation  to  the  physical 
processes  at  work ;  and  then  the  determination  of  the  bearing  of 
these  on  weather  changes.  In  a  footnote  he  instances  the  great  value 
and  interest  a  series  of  cloud  observations  would  have  if  made  hj  a 
society  of  persons  specially  interested  in  cloud  studies  and  observing 
systematically  over  a  large  area  of  country,  "keeping  strictly  to  the 
same  detailed  nomenclature,  e.  g.,  that  of  Clement  Ley." 

There  can  be  no  question  that  forecasting  would  be  more  certain 
if  we  could  connect  certain  types  of  cloud  formation  with  certain 
conditions  of  atmospheric  circulation.  It  being  impossible  to  get 
the  series  of  observations  of  the  character  referred  to,  I  thought  that 
a  rough  approximation  might  he  made  by  carefully  charting  cloud 
observations  made  simultaneously  by  the  observers  of  the  Weather 
Bureau.  The  classification  is  that  of  Luke  Howard,  and  I  can  only 
repeat  here  the  remark  made  in  the  discussion  of  Captain  Toynbee's 
paper  on  cloud  names,  by  Clement  Ley,  viz. :  "  Before  the  dawn  of 
synoptic  meteorology,  Luke  Howard's  system  filled  a  need,  though  it 
did  little  to  promote  inquiry.  Since  that  era  it  may  safely  be  made 
the  basis  of  a  carefully  discriminating  and  eclectic  system  of  termi- 
nology. But  any  endeavor  to  restrict  ourselves  to  its  use  cuts  off 
the  possibility  of  obtaining  what  becomes  more  and  more  necessary, 
viz.,  the  power  of  either  communicating  from  distant  localities  the 
actual  aspect  of  the  sky  so  that  this  may  be  represented  graphically 
or  of  recording  such  an  aspect,  so  as  to  call  up  in  the  mind  a  vivid 
idea  of  the  observed  phenomena ;  I  believe  that  ten  thousand  years 
of  observations  conducted  on  Luke  Howard's  system  would  give  us 
an  absolutely  futile  record."  The  language  is  a  little  strong,  but 
there  is  some  justification  for  it.  However,  it  is  not  altogether  an 
easy  task  to  devise  a  classification  so  detailed  as  to  definitely  picture 
up  any  one  of  the  numerous  and  often  not  easily  definable  sky  aspects. 

Taking,  then,  the  observations  of  the  Weather  Bureau  observers, 
charts  were  made  in  the  Forecast  Room  each  morning  and  night, 
and  prove  first  that  it  is  entirely  practicable  to  construct  such  cloud 
maps  within  the  time  allotted,  and,  second,  that  we  can  make  use 
of  the  same  in  forecasting.  The  particular  point  which  these  bring 
out  is  that  it  is  possible  to  fix  with  considerable  accuracy  the  storm 


CLOUDS    AND    WEATHER    PREDICTION.  23 

center.  We  need,  however,  the  velocities  of  cloud  motion  as  well  as 
the  directions.  And  even  in  getting  direction  there  is  room  for  great 
improvement.  It  should  be  instrumental,  and  not,  as  now,  a  matter 
of  eye  observation.  The  surface  wind  is  represented  by  an  arrow 
flying  with  the  wind  below  the  station,  the  cloud  directions  by  arrows 
above  the  station.  The  velocities  could  easily  be  indicated  by  barbs 
in  the  tail  of  the  arrow.  Where  two  or  more  types  of  clouds  are 
reported,  the  uppermost  arrow  represents  the  uppermost  cloud.  I 
then  employed  the  simple  scheme  of  prolonging  the  arrow  heads  of 
all  lower  directions  and  the  arrow  tails  of  all  upper  directions,  assum- 
ing that  in  this  way  we  can  get  at  not  only  the  general  center  of 
gyratory  motion,  but  if  sufficient  observations  are  at  hand,  the  ten- 
dency to  the  formation  of  any  secondary  center  of  gyratory  motion. 

For  general  forecasting,  therefore,  I  give  it  as  my  opinion,  from 
this  practical  test,  that  cloud  observations  can  be  used  to  great 
advantage.  In  special  forecasting  there  can  be  no  doubt  that  clouds 
should  go  hand  in  hand  with  pressure,  temperature,  and  humidity 
studies.  We  should  have  self-recording  nephoscopes,  and  the  diur- 
nal curves  directly  considered  in  their  relation  to  the  barometer, 
thermometer,  and  h3'^groscope  curves.  To  take  the  single  case  of 
temperature,  every  forecaster  knows  that  any  prediction  as  to  tem- 
perature will  depend  somewhat  upon  the  cloudiness.  It  is  certainly 
marked  in  minimum  and  maximum  temperatures.  The  amplitude  of 
the  daily  temperature  oscillation  will  be  modified  by  the  condition  of 
cloudiness. 

Lamont,'  E.  Quetelet,^  Rykatschef,'  Jesse,  and  Angot  have  shown 
for  Munich,  Brussels,  Saint  Petersburg,  Hamburg,  and  Paris  that  the 
daily  amplitude  is  much  greater  on  clear  days  than  on  cloudy  days. 
It  seemed  to  me  worth  while  to  practically  test  this,  so  I  have  taken 
from  my  paper  on  "  Temperature  Corrections  "  the  mean  amplitudes, 
based  on  some  twelve  years'  observations,  and  charted  with  them 
the  mean  daily  cloudiness  for  a  similar  period.  The  tables  show 
that  in  the  United  States  the  greatest  amplitudes  are  found  with  the 
least  cloudiness,  as  was  to  have  been  expected.  For  example,  at  Win- 
nemucca,  El  Paso,  and  Yuma,  where,  on  a  scale  of  10,  the  mean 
annual  cloudiness  is  3  or  less,  the  values  of  the  amplitude  approach 
25°  F.  (13.9°  C);  and  on  the  other  hand,  at  Toledo,  Cleveland,  or 
Eastport  the  cloudiness  is  much  greater,  about  5,  the  mean  ampli- 
tudes are  much  smaller,  about  12°  F.  (6.7°  C). 

^Darstellung  der  Temp.-Verhaltnisse,  etc. 
*Memoire  sur  la  Temp.,  etc. 
'  La  marche  diurne  de  la  Temp. 


24 


CHICAGO    METEOROLOGICAL    CONGRESS. 

Temperature  amplitudes  and  mean  cloudiness. 


Station. 


19. 


Winnemucca,  Nev.: 

OF 

OC 

Clouds I    4 

Yuma,  Ariz.: 

OF 

OC 

Clouds 

Washington,  D.C.: 

OF 

OC 

Clouds 

Philadelphia,  Pa.: 

OF 

OC 

Clouds 

Salt  Lake  City, Utah 

op 

°  c'.'.'.'.'.'.'.'.'.'.'.'.'.'.. 

Clouds 

Saint  Louis,  Mo.: 
op 

°c'.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 

Clouds 

New  Orleans,  La.: 

OF 

OC 

Clouds 

Memphis,  Tenn.: 

°C. '.'.'.'.'.'.'.'.'.'.'.'.'.'. 

Clouds  

Santa  Fe,N.Mex.: 

OF 

OC 

Clouds 

Buffalo,  N.Y.: 

op 

°  c'.'.'.'.'.'.'.'.'.'.'.'.'..'. 

Clouds  

Montgomery,  Ala.: 

OF 

OC 

Clouds  

San  Diego,  Cal.: 

op 

OC 

Clouds 

San  Francisco, Cal.: 

''F 

OC 

Clouds 

Denver,  Colo.: 

OF 

OC 

Clouds 

Atlanta,  Ga.: 

op 

OC 

Clouds 

El  Paso,  Tex.: 

op 

OC 

Clouds 

Milwaukee,  Wis.: 

OF 

OC 

Clouds  

Cheyenne,  Wyo.: 

op 

OC 

Clouds  

Savannah,  Ga.: 

°F 

OC 

Clouds 

Chicago,  111.: 

op 

OC 

Clouds 


3-8 


17.8 
9.9 
4.6 


21.6 
II.  4 
3.8 


23.6 

13-1 
2.2       2.2 


10.8 
6.0 
5-6 

8.0 
4.4 
5-2 

10. 1 
5-6 
5-4 

9.8 

5-4 
5-3 

9.6 
5-3 
5-0 

10.  o 
.S.6 
5-7 

17.0 
9.4 
3-7 

4.8 
2.7 
6.6 

12.7 
7-1 
5-5 


II. 7 
6.5 
5-4 

10.  o 

5-6 
5-5 

13-4 
7-4 
5-0 

11.6 
6.4 

5-4 


6.2 
4.9 

11.8 
6.6 
5-1 

19.4 
10.8 
3-6 

5-7 
3-2 
6.4 

14.4 
8.0 
4-7 


12.4  I  II. I 

6.9  I  6.2 

4. 1  I  4.8 

7.2  j  8.0 
4.0  1  4.4 
4.6  I  4.6 


16.0 

8.9 ;  9 


16.8 
3 

3-5  ! 

1 

10.8  i 

6.0  i 

5-3  1 

23-3 
12.9 
3-0 


18.8 
10.4 


6 

7.2 

7 

4.0 

0 

5-8 

6 

13-4 

0 

7-4 

5 

3-5 

0 

12. 1 

I 

6.7 

0 

4.8 

8 

7.8 

8 

4-3 

7 

5-5 

12.6 
7.0 

4.6 

24.6 

13-7 
2.7 

7-4 
4.1 
6.0 

l6.8 
9-3 

4.2 

13-2 
7-3 
4-3 

7-7 

4-3 
5-8 


>. 

0, 

< 

s 

* 

21.0 

23-4 

II. 7 

13.0 

4.2 

3-9 

28.2 

27.6 

is.b 

15-3 

1.6 

1.2 

14.7 

15-2 

8.2 

8.4 

5-3 

5-0 

12.6 

I.V6 

7.0 

7.6 

5-3 

4.8 

14.0 

I,V6 

7.8 

8.7 

5-2 

4-5 

13-4 

13-2 

7-4 

7-3 

5-0 

4.9 

10.4 

10.8 

5-8 
4.8 

12.4 
6.9 
4-7 

17.4 
9-7 
4-1 

7-9 

4.4 

5-5 

16.2 
9.0 
4.6 

10.4 

5-8 
4.6 


4.8 
4.2 

18.8 
10.4 
4.9 

14-3 
7-9 
4-5 

26.2 
14-5 
2-3 


4.6 
5-6 

17.9 
9.9 
4.9 

II. 9 
6.6 


7-5 
4.2 

5-2 


6.0 

4-8 

14.2 

7-9 
4.6 


25-8 
14-3 
3-2 

28.3 
15-7 
0.8 

14.7 
8.2 
4.9 

13.0 
7.2 
4-7 

17-7 
9.8 
3-2 

13.0 
7.2 
50 

8.4 
4-7 
4-5 

12.6 
7.0 
4-5 


19-5 
10.8 
3-8 

22.0 
12.2 

3-3 

20.0 
II. I 

4.8 

9.0 
5-0 
5-2 

8.1 
4-5 
4.8 

8.2 
4.6 
3-6 

15-4 
8.6 
4.4 

14.7 
8.2 
5-1 

14.4 
8.0 
4.9 

9.8 
5-4 
5-4 

9.4 
5-2 
5-1 

9-5 
5-3 
4-7 

9.4 
5-2 

4.0 

9-5 
5-3 
4.0 

10. 1 

4.6 

19.6 
10.9 
4.9 

22.8 
12.7 
3-7 

22.8 
12.7 
4.2 

12.8 

7-1 
4.6 

12. 1 
6.7 
5-2 

12.2 
6.8 
4.6 

26.6 
14.8 
2.4 

27.6 

15-3 
2.8 

25.0 
13-9 
3-7 

7.6 
4.2 
5-0 

7.8 
4-3 
5-0 

9.6 

5-3 
4.4 

20.7 

"•5 
5-1 

23-8 

13-2 

3-9 

24.2 
13-4 
3-9 

II. 4 
6-3 
4.2 

6-3 
4.9 

10.8 
6.0 
4.8 

7.0 
3-9 
4-7 

7.6 
4.2 
4.9 

8.8 
4.9 
3-9 

29.8 
16.5 

1-7 

24.0 
13-3 
1-7 

14.4 
8.0 
4.6 

12.8 

7-1 
4.8 

19.6 
10.9 
3-0 

14. 1 

7.8 
4.2 

9.0 

5-0 

4-8 

13.6 
7.6 
4.2 


33-8  3I' 

18.8  17.3 

1.4  I     1.9 

24.2  j  24.8 

13-4  !  13-8 
2.2 

14.8  14. 
8.2       8.2 

4.9       4.7 


12. 1 
6.7 

4-7 

18.4 
10.2 
3-1 

14.0 

7.8 
3-8 

7.6 
4.2 
4.6 

13-8 
7-7 
4.0 

18.2 
10. 1 
4-7 


12.0 
6.7 
4.6 

18.4 


14.8 


9.2 
5-1 
4-5 

14.2 

7-9 
4.0 

18.7 
10.4 
3-0 


10.3       9.9 

5-7  I    5-5 
4.4       5.0 


14-9 
8-3 
4.9 


15-7 

8.7 
4-,S 


9.9  ,  10.5 
5-5  I  5-8 
4.0       3.8 


5-7 
4-3 

1U.7 
5-9 

3-4 

22.1 
12.3 
4.2 

24.2 
13-4 
3-0 

12.7 
7-1 
5-0 

13-4 
7-4 
4-3 

23.8 
13-2 
3-5 

24.1 
13-4 
2.9 

9-7 
5-4 
4.6 

10.9 
6.1 
4.9 

23.6 

3-8 

24.4 
13-5 
3.2 

9.8 
5-4 
5-0 

6-3 
4.8 

9.0 

10.2 

5-0 
3-9 

5-7 

4.3 

27.2       22.8 

15. I  !  12.7 

2.6  j  3.6 

24.6 

13-7 


15-1 
8.4 
4-7 


6.2 
4.6 

14.0 
7.8 
3-7 

13- 2 
7-3 

3-8 

9.6 
5-3 
3-9 

14.2 
7-9 
3-8 

19.0 
10.6 
2.4 

7-3 
4.1 
6.0 

15-9 
8.8 
4.1 


II. 2 

6.2 

11.9 
6.6 

3-9 

3-5 

10.2 

8.0 

5-7 
3-2 

4.4 
3-8 

20.6 

18.4 

11.4 

10.2 

3-5 

3-3 

13-6 
7.6 
4.2 

12.4 
6.9 

4.6 

25-6 
14.2 

2-5 

23-8 
13-2 
3-1 

8.4 

4-7 
5-5 

6.7 
3-7 
6-3 

19.2 
10.7 
3-7 

15-6 
8.7 
3-6 

12.0 
6.7 

12.2 

6.8 

4.0 

4-5 

8.8 
4.9 
5-0 

7-3 
4.1 
5-8 

CLOUDS    AND    WEATHER    PREDICTION. 


25 


No  paper  upon  cloud  work  would  be  complete  without  reference  to 
the  work  of  Ekholm,  Hagstrom,  and  Hildebrandsson  in  putting  before 
us  the  question  of  cloud  measurements.  And  I  must  not  omit  ref- 
erence to  the  law  of  relative  directions  of  lower  and  upper  currents 
as  announced  by  Ley — high  currents  coming  from  a  direction  to  the 
right  of  the  lower  currents,  and  the  higher  up  the  more  marked  this 
twist.  Or  in  Ferrel's  words  "The  higher  currents  of  the  atmosphere 
while  moving  commonly  Avith  the  highest  pressures,  in  a  general  way 
on  the  right  of  their  course,  yet  manifest  a  distinct  centrifugal  ten- 
dency over  the  areas  of  low  pressure  and  a  centripetal  over  those  of 
high."  It  is  also  not  out  of  place  to  mention  briefly  the  more  prom- 
inent of  the  proposed  cloud  systems,  viz.,  Luke  Howard's,  the  essay 
read  before  the  Askesian  Society,  1802-1803 ;  Clement  Ley's  observa- 
tions ;  Abercromby  and  Hildebrandsson's ;  Wilson-Barker's ;  Aber- 
cromby's ;  Hildebrandsson  and  Neumayer's ;  Dr.  Carl  Singer's ;  Kop- 
pen  and  Neumayer's ;  Dr.  Vettin's  table  of  average  altitudes,  and  the 
work  at  Blue  Hill  in  this  country.  As  a  matter  of  perhaps  more 
literary  than  scientific  value,  I  append  a  list  of  English  cloud  desig- 
nations. 

List  of  English  cloud  designations. 


Alto-cirrus,  alto-cumulus. 

Ark  o'  the  cluds. 

Auroral  clouds. 

Balefrae — bale  fire. 

Ball  clouds,  bally. 

Banner,  banneret. 

Bise. 

Buddha's  rays. 

Catstails. 

Cirrus,  cirro-cumulus,  cirro- 
filum,  cirro-nebula,  cirro- 
haze,  cirro  -  stratus,  cirro- 
stripes,  cirro-velum. 

Cloud,  cloud  area,  cloud  bank, 
cloud  ring,  cloud  ship,  cloud 
wrack,  cloud  wreath,  cloud 
wraith. 

Cormizant. 

Corposant. 

Coronfe. 

Cumulus,  cumulo-cirrus,  cu- 
mulo-nimbus, cumulo- 
stratus. 

Dapple  sky. 

Dark  segment  (auroral). 

Diablaton. 

False  cirrus. 

Festooned,  festooned  cumulo- 
cirrus,  festooned  cumulus, 
festooned  stratus. 

Filly  tails. 


Fireballs. 
Fog  bow. 
Fracto  -  cumulus,    fracto- 

nimbus. 
Funnel-shape. 
Globo-cumulus. 
Goats  hair. 
Helm-bar. 
Henscat. 
Iridescent. 
Leeside. 
Luminous. 
Mackerel  sky,  mackerel 

scales,  mackerel  back. 
Mammato-cumulus. 
Mary's  ship. 
Mare's  tails. 

Merry  dancers  (auroral). 
Nacreous. 
Nightcap. 
Nimbus. 
Noah's  ark. 
Nimbo  -  pallium,   nimbo- 

stratus. 
Packet  boys. 
Pallio-stratus. 
Pallium. 
Pocky  cloud. 
Prophet  cloud. 
Plague  cloud. 
Polar  bands. 


Rain  balls,  rain  clouds, 
rainbow. 

Radiation  fog. 

Rime  cloud. 

Rocky. 

Roll  cumulus. 

Salmon. 

Scud. 

Scotch  mist. 

Saint  GJara's  fire. 

Saint  Elmo's  fire. 

Snow  banners. 

Spindrift. 

Storm  cloud. 

Snow  cloud. 

Spectre  of  Brocken. 

Stratus,  strato  -cirrus, 
strato-cumulus. 

Tablecloth. 

Thunder  heads,  thunder- 
squall  clouds. 

Turreted  cumulus. 

Tornado. 

Unraveled. 

Watery  sky. 

Weather  lights. 

Woolly  heads. 

Wulst  cumulus. 

Wool  bags. 

Wrack. 

Wraith. 


26  CHICAGO    METEOROLOGICAL    CONGRESS. 


7.— AN  INTERNATIONAL  CIPHER  CODE  FOR  CORRESPOND- 
ENCE RESPECTING  THE  AURORA  AND  RELATED  CON- 
DITIONS. 

Dr.  M.  AJ  Veedeb. 

It  is  presumed  that  the  assignment  of  this  subject  to  the  writer  is 
intended  to  call  for  the  results  of  the  experience  which  he  has  had 
in  attempting  to  secure  concerted  observations  of  the  aurora.  The 
adoption  of  a  special  plan  of  observation  or  code  correspondence 
respecting  such  a  phenomenon  as  the  aurora  presupposes  the  selection 
of  the  points  thought  to  be  most  important  in  order  that  they  may- 
be made  the  subject  of  special  observation  and  record  for  purposes  of 
interchange  and  comparison.  The  purpose  in  view  in  any  such  case 
determines  the  character  of  the  record  to  be  made.  If  the  plan  involves 
nothing  more  than  the  preservation  of  memoranda,  such  as  may 
happen  to  be  secured  incidentally  in  the  ordinary  course  of  meteoro- 
logical observation,  and  without  reference  to  the  requirements  of 
serious  study,  it  is  scarcely  worth  while  to  discuss  the  subject  at  any 
great  length  or  offer  many  suggestions. 

All  that  can  be  expected,  if  nothing  more  than  this  is  to  be  attempted, 
is  the  recording  of  dates  and  localities  with  perhaps  some  items  of 
description  more  or  less  condensed,  it  may  be,  by  the  aid  of  the  sys- 
tems of  classification  already  in  ordinary  use  which  have  reference  to 
the  presence  or  absence  of  arches,  streamers,  auroral  waves,  the  corona, 
and  the  like.  Still,  the  gathering  into  suitable  records  and  making 
accessible  information  not  more  complete  than  this,  has  iieen  the 
means  of  affording  a  knowledge  of  certain  broad  features.  The  rela- 
tive prevalence  of  the  aurora  in  different  years  and  its  conformity  to 
the  records  oFsun  spots  and  magnetic  storms  has  thus  been  shown,  as 
has  also  the  predominance  of  auroras  near  the  equinoxes,  and  at 
intervals  of  about  twenty-seven  days,  corresponding  to  the  time  of  a 
synodic  rotation  of  the  sun.  By  such  means  also  the  distribution  of 
the  aurora  in  belts  surrounding  the  magnetic  poles  has  become  known. 
If  so  much  is  to  be  learned  by  the  aid  of  observations  that  have  been 
for  the  most  part  little  better  than  merely  desultory,  what  might  not 
be  expected  from  the  elevation  of  the  subject  into  a  special  depart- 
ment of  research  to  be  undertaken  formally  and  of  set  purpose? 

In  the  paper  on  the  "  Periodic  and  Non-periodic  Fluctuations  in 
Latitude  of  Storm  Tracks,"  presented  by  the  writer  in  the  Section 
of  Marine  Meteorology  of  this  Congress,  it  is  shown  that  important 
relations  to  meteorology  may  be  involved  in  the  operation  of  the 
forces  concerned  in  the  production  of  the  aurora.  This  being  the 
case,  its  behavior  is  as  worthy  of  careful  record  as  is  temperature, 
pressure,  or  any  other  meteorological  element. 

The  experience  which  the  writer  has  had  in  this  regard  has  had 


INTERNATIONAL    CIPHER    AND    AURORAS.  27 

reference  more  particularly  to  methods  of  recording  observations, 
and  not  to  any  system  of  code  correspondence  based  thereon.  A 
specimen  of  the  forms  which  he  has  employed  for  securing  such 
records  is  appended  to  this  paper.  The  points  upon  which  the 
greatest  possible  stress  is  laid  are  the  giving  of  the  times  of  observa- 
tions and  of  all  prominent  features,  and  the  noting  specifically  of 
verifications  of  the  absence  of  the  aurora  as  well  as  its  presence,  and 
the  recording  of  frequent  estimates  of  the  extent  of  sky  covered.  By 
the  aid  of  such  data  it  becomes  possible  to  attack  the  questions  as  to 
geographical  distribution,  altitude,  coincidence  with  magnetic  per- 
turbations, and  the  like,  positively  and  directly,  and  not  remotely  and 
inferentially. 

Some  of  the  results  of  this  system  of  observation  are  indicated  in  the 
paper  on  Storm  Tracks,  to  which  reference  has  been  made,  and  in  other 
notes  and  articles  of  similar  tenor,  and  do  not  need  to  be  rehearsed  in 
the  present  connection.  Suffice  it  to  say  that  the  observations  recorded 
in  this  precise  way  are  proving  to  be  extremely  valuable. 

As  regards  the  general  descriptions  to  be  given  in  connection  with 
these  observations,  it  is  found  that  great  freedom  and  fullness  in  giv- 
ing details  are  very  desirable.  Not  unfrequently  items  of  description 
that  would  be  omitted  in  a  code  system  of  abbreviating  and  summar- 
izing prove  to  be  of  the  very  highest  interest.  Further  experience  is 
required  before  it  can  be  fully  known  what  points  are  of  such  imme- 
diate and  practical  interest  as  to  justify  or  require  the  adoption  of  so 
elaborate  an  arrangement  as  an  international  cipher  code  for  their 
communication.  Still,  there  are  indications  that  something  in  this 
line  is  worth  attempting,  and  that  the  time  is  surely  coming  when  a 
system  of  correspondence  having  reference  to  the  whole  range  of  phe- 
nomena of  which  the  aurora  is  the  visible  expression  will  be  well 
nigh  indispensable  for  purposes  of  weather  predictions  as  well  as  the 
advancement  of  general  scientific  research.  It  will  not  be  advisable, 
perhaps,  to  be  too  urgent  in  attempting  to  bring  about  such  an  ar- 
rangement prematurely.  Not  until  the  facts  and  principles  involved 
are  fully  appreciated  and  recognized  by  the  scientific  world  generally 
will  the  demand  for  the  adoption  of  an  international  code  system 
become  so  emphatic  that  it  can  not  be  disregarded. 

The  question  now  is  as  to  the  best  means  of  arousing  such  lively 
interest  most  rapidly  and  effectually.  It  will  contribute  somewhat 
to  this  end,  perhaps,  and  compel  attention  to  the  merits  of  the  case, 
to  describe  briefly  what  would  be  an  ideal  system  of  inter-communi- 
cation at  the  present  stage  of  progress  of  the  research  respecting  the 
aurora  and  related  conditions. 

If  there  could  be  brought  together  upon  daily  synoptic  charts,  along 
with  other  meteorological  data  which  it  is  now  customary  to  present 
in  this  way,  information  also  in  respect  to  all  auroras  seen  over  as 


28  CHICAGO    METEOROLOGICAL    CONGRESS. 

wide  an  area  as  possible,  and  likewise  some  indication  of  the  extent 
of  prevalence  of  thunderstorms,  together  with  notes  from  the  mag- 
netic observatories  as  to  the  times  and  extent  of  any  perturbations 
recorded,  and  information  also  as  to  the  geographical  distribution  of 
any  earth-currents  that  may  have  been  felt  on  the  telegraph  lines, 
and  in  addition,  some  description  of  the  coincident  solar  conditions 
on  which  this  class  of  phenomena  evidently  depends,  any  characteris- 
tic relations  to  intensification  of  storms  or  changes  in  the  distribu- 
tion of  atmospheric  pressure  would  soon  become  apparent.  Such  an 
arrangement  would  require  simply  an  extension  of  the  telegraphic  code 
system  now  in  ordinary  use  for  the  communication  of  meteorological 
data  so  as  to  comprise  features  not  heretofore  taken  into  the  account. 

It  is  evident  that  even  tentative  efforts  in  this  direction  would 
arouse  a  lively  interest,  and  would  certainly  stimulate  criticism  which, 
whether  adverse  or  favorable,  would  tend  to  increase  of  knowledge,  such 
as  could  never  result  from  the  utter  stagnation  and  neglect  to  which 
this  class  of  research  has  been  subjected  for  extended  periods.  Such 
a  plan  would  inevitably  bring  to  a  practical  test  the  suggestions  that 
have  been  made  in  various  quarters  recently  as  to  the  part  which 
electro-magnetic  forces  of  solar  origin  play  in  atmospheric  control, 
and  would  tend  to  eliminate  errors  and  crudities  which  are,  to  a  cer- 
tain extent,  unavoidable  in  the  prosecution  of  a  new  line  of  research, 
and  if  there  be  a  residuum  of  truth  it  would  be  shown  bej^'ond  a  per- 
adventure,  and  its  practical  value  demonstrated. 

These  suggestions  are  the  outgrowth  of  the  practice  which  the  writer 
has  maintained  for  many  years  of  journalizing  phenomena  of  this 
class  on  a  daily  record.  As  the  result,  the  conviction  has  grown  that 
the  principle  of  electro-magnetic  induction  of  dynamic  origin  plays 
a  far-reaching  part  in  the  economy  of  the  solar  system,  and  that  it  is 
concerned  in  atmospheric  control  in  ways  that  are  only  just  beginning 
to  be  understood.  From  his  point  of  view,  therefore,  the  scheme  of 
communicating  and  recording  observations  above  described  is  well 
worth  trying.     How  it  will  impress  other  minds  remains  to  be  seen. 

[Copy  of  form  used  by  the  Peary  Arctic  Expedition  in  recording  auroral  phenomena.] 

Name  and  address  of  observer Date 189 

Latitude  and  longitude  of  station Kind  of  time  used 

Observations  of  the  aurora  in  co-operation  with  Civil  Engineer  Peary,  U.  S.  N., 
in  Northern  Greenland,  are  to  be  entered  as  follows :  The  absence  of  the  aurora  is 
to  be  indicated  by  entering  in  the  proper  space  the  figures  showing  the  minutes  of  the 
hour  during  which  such  absence  was  verified  by  observation.  Thus  the  entry  "0-10" 
in  the  column  headed  7  to  8  p.  m.  would  be  understood  as  showing  that  observations 
were  made  from  7.00  to  7.10  p.  ra.  and  that  there  was  no  aurora  at  that  instant.  If 
observation  is  impossible  from  cloudiness  or  any  cause  it  will  be  sufficient  to  leave 
the  spaces  entirely  blank.  The  presence  of  the  aurora  is  to  be  indicated  by  writing 
Aurora  in  the  proper  s{)ace  and  giving  the  exact  times  and  other  items  under  the  head 
of  Descriptions.  No  matter  what  else  may  be  recorded,  it  is  of  the  utmost  importance 
to  give  as  accurately  as  possible  the  times  of  any  sudden  increase  or  diminution  in 


METHOD    OF    TESTING   PREDICTIONS. 


29 


brightness  of  displays,  together  with  estimates  of  the  extent  of  sky  covered  and  its  posi- 
tion relative  to  the  true  north.  Minute  descriptions  of  the  formation  of  arches, 
streamers,  prismatic  colors,  and  the  like,  accompanying  such  variations  in  the  extent  of 
displays,  are  of  interest,  but  are  far  less  important  than  that  the  times  should  be 
noted  as  accurately  as  possible.  A  pencil  and  paper  carried  in  the  pocket  to  note  the 
times,  etc.,  for  the  purpose  of  transference  to  the  blanks  will  be  found  to  be  the  most 
convenient  plan,  and  will  enable  memoranda  to  be  preserved  that  would  otherwise  be 
lost.  Even  scanty  records  when  kept  upon  this  precise  plan  may  yield  most  valuable 
results,  for  it  is  impossible  to  tell  in  advance  of  comparison  with  others  what  particular 
entry,  whether  of  the  presence  or  absence  of  the  aurora,  may  be  found  to  be  of  the  very 
highest  interest.  In  the  present  instance  the  Arctic  records  will  be  continuous  when- 
ever observation  is  possible,  relays  of  observers  connected  with  the  expedition  relieving 
each  other.  The  records  when  complete  may  be  returned  to  M.  A.  Veeder,  Lyons, 
New  York,  U.  S.  A.,  who  will  supply  blanks  and  all  information  desired. 


Date. 

6  to  7  p.  m. 

7  to  8  p.  m. 

8  to  9  p.  m. 

9  to  10  p.  m. 

10  ton  p.m.  II  to  12  p.m. 

i 

12  to  6  a.m. 



DESCRIPTIONS. 


8.— THE   BEST  METHOD   OF  TESTING  WEATHER  PREDICTIONS. 

Prof.  Dr.  W.  Koppen. 

When  weather  predictions  are  issued,  naturally  there  follows  the 
wish  of  the  authors  to  determine  their  trustworthiness.  If  one  fol- 
lows this  idea,  it  is  necessary  to  decide  between  the  various  methods 
of  verification.  For  this  purpose  the  object  must  correspond  with 
that  which  is  followed  in  the  verification  of  the  predictions. 

If  it  is  desired  to  facilitate  a  conclusive  investigation  of  the  rela- 
tion between  predictions  and  the  weather,  both  must  be  dealt  with 
by  the  same  method,  as  one  would  investigate  the  connection  between 
two  meteorological  factors.  It  must  be  pointed  out  that  predictions 
and  the  ensuing  weather  bear  the  relation  to  each  other  of  two 
dependent  functions  and  what  conditions  this  relation  implies.  It 
should  be  shown  how  different  kinds  of  weather  follow  different  pre- 
dictions, as  we  show  that  different  wind  directions  are  followed  by 
different  temperatures,  etc. 

The  matter  is  simplest  when  one  has  to  deal  with  predictions  con- 
cerning which  it  is  doubtful  whether  they  really  have  a  basis  or 
whether  they  are  to  be  regarded  as  pure  chance  predictions,  as,  for 
example,  when  both  are  based  on  the  moon's  phases.  It  is  clear  that 
even  chance  predictions  must  give  a  certain  percentage  of  success.  If, 
however,  the  real  weather  be  put  after  the  predictions  under  different 
headings,  it  becomes  evident  whether  these  figures  are  due  only  to 


30  CHICAGO    METEOROLOGICAL    CONGRESS. 

chance  or  to  the  knowledge  (even  if  it  be  occult)  of  certain  laws,  since, 
in  the  latter  case,  the  weather,  according  to  opposite  predictions,  would 
have  been  sensibly  different,  while  in  the  first  case  it  would  remain 
the  same.  The  supposition  is  always  that  a  sufficiently  large  number 
of  predictions  has  been  included  in  the  verification,  since  so  long 
as  the  law  of  large  numbers  does  not  enter,  the  separation  between 
chance  and  law  is  destroyed  and  no  argument  is  possible,  unless  it 
be  that  the  prognosticator  is  not  infallible. 

For  a  better  understanding  of  the  above  let  us  take  an  example 
from  the  summer  of  1883.  There  were  two  kinds  of  predictions  in- 
vestigated, which  we  will  designate  by  classes  A  and  B.  The  second 
columns  give  the  contents  of  the  predictions : 


The  succeeding  weather  was- 


Class  A ; 
Warm 
Cold  .. 

Class  B: 
Warm 


Warm,     j    Normal.  Cold. 


Per  cent.    ]    Per  cent. 

17  I  33 

14  I  32 


77  1  15 

Cold I  0,  5 


Per  cvnt. 

54 


It  is  seen  that,  according  to  the  prediction  "A,"  the  real  weather 
remained  the  same  whether  the  prediction  read  either  warm  or  cold, 
but  showed  a  marked  contrast  with  respect  to  the  prediction  "B." 
Now  the  predictions  "A"  (made  for  a  month  in  advance)  are  true 
chance  predictions,  although  they  excited  great  surprise  and  by  many 
are  regarded  as  satisfactory.  "B"  are  synchronous  daily  predictions 
of  a  meteorological  institute.  In  cases  of  this  sort  this  method  is 
entirely  conclusive  and  sufficient. 

Concerning  the  "  B  "  predictions,  this  table  shows  that  between  them 
and  the  following  weather  there  exists  an  evident  relation.  In  general 
there  can  be  no  question  as  to  the  predictions  for  only  twenty-four 
hours  ahead.  Even  with  the  most  unskilful  predictor  there  would  be 
a  general  agreement  for  so  short  a  time.  It  is  to  be  asked,  therefore, 
how  close  this  connection  is,  and,  indeed,  if  this  relation  can  be 
expressed  by  a  single  numerical  value.  Detailed  researches  on  the 
subject  show  that,  unfortunately,  a  series  of  unknown  values  enters, 
and  that  an  irreproachable  derivation  of  such  a  simple  number  for 
the  expression  of  the  worth  of  a  prediction  is  impossible — almost  as 
impossible  as  to  estimate  the  value  of  a  person  or  a  nation  by  a 
numerical  expression.  Such  expressions  have  been  proposed,  for 
example,  in  America  in  1884,  by  Messrs.  G.  K.  Gilbert  and  C.  S.  Peirce, 
but  the  formulae  given,  although  ingenious,  are  one  sided,  and  have 
not  a  universal  application. 

Still  less,  as  a  measure  of  the  value  of  a  prediction,  can  the  usual 


METHOD    OF    TESTING    PREDICTIONS.  31 

percentage  of  success  be  used  in  which  the  influence  of  chance  is 
neglected  and  the  phenomena  are  treated  without  regard  to  their 
frequency.  If  one  wishes  to  have  an  answer  to  the  question,  how 
often  a  certain  prediction  is  followed  by  such  and  such  weather, 
without  regard  to  the  reason,  naturally  such  a  calculation  of  per- 
centage is  quite  satisfactory,  only  in  the  first  place  we  do  not  know 
what  this  can  teach  us,  and  secondly,  as  we  shall  see  directly,  from 
the  method  of  calculation  it  is  largely  influenced  by  the  personal  in- 
terpretation of  the  verifier.  It  is,  for  example,  very  instructive  to 
know  that  the  2,803  cases  of  tornado  predictions  are  so  divided  that 
in  2,703  cases,  when  no  tornado  was  predicted,  in  only  23  was  one 
observed,  in  2,680  cases  not,  and  among  the  100  cases  where  tornadoes 
were  foretold  they  happened  in  28  cases  and  did  not  occur  in  72. 


No  tornado  predicted , 
Tornado  predicted  — 


Tornado  occurred. 

No  tornado. 

Per  cent. 

Per  cent. 

1 

99 

28 

72 

From  this  statement  it  is  seen  that  the  predictor  has  in  the  last 

cases  found   the  tendency  to  tornado  formation.      But  what  good 

2708 
is  it  when  the  fraction  =  96.61  is  given  as  the  percentage  of 

success  of  this  prediction,  a  seemingly  high  number,  but  which  is, 

nevertheless,  inferior  to  that  which  would  be  had  if,  without  trouble, 

a  daily  prediction  of  "no  tornado"  had  been  made,  for  then  this 

2752 
number  would  be  ^-— —  =  98.18  per  cent. 

The  second  cause  which  makes  the  value  of  the  percentage  of  suc- 
cess, as  usually  calculated,  seem  very  small,  is  the  indefinite  nature 
of  the  fundamental  material,  and  therefore,  the  consequent  impossi- 
bility of  making  the  verification  comparable. 

The  determination  of  what  follows  a  prediction  has  been  generally 
sought  on  the  basis  of  the  verification  of  the  general  character  of 
the  day  over  a  large  territory,  which  is  fixed  by  estimation.  As  to 
the  sincere  general  wish  to  get  at  the  truth  by  this  estimation  there 
can  be  no  doubt.  Only  according  to  the  interpretation  of  the  words 
and  the  pessimistic  or  optimistic  tendency  of  the  verifier  such  esti- 
mates must  difl^er  greatly ;  and  even  when  in  an  institute,  by  precise 
instructions  they  are  rendered  independent  of  the  person,  it  will 
never  be  possible  to  introduce  such  instructions  and  their  interpre- 
tation in  other  institutes,  or  even  to  render  them  so  invariable  at  the 
same  institute  that  slight  changes  in  their  application  will  not  afi:ect 
the  results  in  an  uncontrollable  manner.  For,  in  order  to  determine 
the  influence  of  each  of  these  rules  or  usages  on  the  result,  compre- 
hensive investigations  would  be  needed,  which  have  not  yet  been  made 
and  for  which  time  would  be  required  that  could  better  be  used  in  the 


32  CHICAGO    METEOROLOGICAL    CONGRESS. 

extension  of  the  basis  of  weather  predictions.  Besides,  these  per- 
centages of  success,  although  as  a  rule  they  are  understood  to  be  the 
relation  which  the  successful  predictions  bear  to  the  whole  number, 
yet  they  are  generally  to  be  considered  as  the  means  of  the  tests 
which  the  prediction  would  give  if  arranged  in  various  gradations. 
Thus,  most  of  the  German  institutes  have  arranged  the  predictions 
according  to  their  results  in  three  grades — the  Bavarian  Institute, 
since  January,  1882,  has  used  five  grades — whose  values  are  100,  50, 
and  0,  or  100,  75,  50,  25,  and  0,  as  percentages  of  their  entire  accur- 
acy, but  the  arithmetical  mean  of  these  numbers  has  been  taken  as 
the  percentage  of  success  of  the  prediction. 

For  the  above  reasons,  at  the  Seewarte  since  1886  the  calculation 
of  percentages  of  success  has  been  abandoned,  and  in  its  place  statis- 
tical summaries  in  the  form  already  indicated,  with  as  accurate  a 
basis  as  possible,  have  been  introduced.  Also,  in  the  Monthly  Weather 
Review  of  the  Washington  Weather  Bureau,  since  January,  1892,  the 
heading  "  Verifications  "  has  disappeared — a  sign  that  at  this  great 
institute  the  value  of  these  numbers  is  less  considered  than  formerly.^ 

The  method  followed  by  the  Seewarte  carries  out  these  principles : 

1.  In  place  of  an  approximate  representation  of  the  whole  space 
and  time  covered,  a  precise  determination  is  given  for  8  a.  m.  and  2 
p.  m.  at  only  three  places  in  the  German  Empire. 

2.  For  this  verification  the  conditions,  as  shown  by  the  meteoro- 
logical observations,  are  laid  down  in  the  following  scheme : 

8  a.  m.  2  p.  m. 

November  4 k  u  I  e  d  n  u  m  s  h 

Novembers w  z  I  w  b n  z  m  n  r 

In  which  place  1  gives  the  deviation  of  the  temperature  from  the 
normal :  k  =■  cold  (negative  deviation  greater  than  2°) ;  w  =  normal 
(deviation  0  to  2°) ;  iv  :=  warm  (positive  deviation  greater  than  2°). 
Place  2  gives  temperature  change  in  twenty-four  hours :  a  =  de- 
crease; ?t  =  stationary  (change  less  than  1°);  2  =  increase.  Place 
3  gives  the  wind  force:  I  =  light  (0  to  2),  m  =  moderate  (3  to  4), 
etc.  Place  4  gives  the  wind  direction.  Place  5  gives  the  precip- 
itation. 

3.  As  far  as  the  determination  of  the  expression  permits,  the  pre- 
dictions are  also  arranged  in  the  same  way  in  classes,  and  then  the 
agreement  of  predictions  and  weather  are  worked  up  in  comprehensive 
calculations  and  put  in  a  tabular  form.  Further  details  will  be  found 
in  the  monthly  reports  of  the  Seewarte  from  1886-1891,  and  especially 
in  a  supplement  for  1886. 

Starting  from  similar  ideas,  the  storm  warnings  of  the  Seewarte 


'  The  calculation  of  the  percentages  of  verifications  has  not  been  abandoned,  but  the 
results  instead  of  being  published  monthly  in  the  Weather  Review  are  published  annu- 
ally in  the  Annual  Report  of  the  Chief  of  the  Weather  Bureau. — Editor. 


METHODS    OF    TESTING    PREDICTIONS.  33 

since  1886  differ  from  those  previously  verified,  and  in  this  way — by 
a  representation  of  the  changes  in  the  wind  velocity  according  to  the 
anemometer  indications  at  the  normal  observing  stations  of  the 
Seewarte  in  the  six  hours  preceding  and  in  the  thirty-six  hours  fol- 
lowing each  storm  warning. 

The  comprehensive  tables  which  have  been  compiled  and  published 
by  the  Seewarte  present  much  material  for  study  which  is  well  con- 
solidated and  is  thoroughly  controllable  and  comparable.  Herein  is 
a  precise  answer  to  many  questions  whose  clear  comprehension  and 
solution  are  of  great  importance  for  the  use  of  the  prediction  service. 
For  making  up  reports  to  the  public,  on  the  contrary,  they  are  too 
complicated,  and  demand  more  knowledge  of  the  difficult  questions 
concerning  calculation  of  probabilities  than  is  often  found.  The 
ultimate  question,  which  for  practical  purposes  is  preeminent,  is, 
what  is  the  value  of  weather  predictions  ?  Still,  this  question  must 
remain  under  all  circumstances  unsettled,  no  matter  how  many  or 
how  well  founded  are  the  figures  cited  concerning  the  measure  of  the 
success  of  the  predictions.  When,  for  example,  an  accuracy  of  80  per 
cent  is  found  for  the  prediction,  one  person  may  consider  this  per- 
centage as  very  good,  another  that  the  20  per  cent  of  failure  is  suffi- 
cient to  invalidate  it,  a  third  may  say  that  he  does  not  find  just  what 
he  needs  in  the  prediction,  the  fourth  may  state  that  the  prediction 
is  worthless  if  it  does  not  come  to  him  sooner,  the  fifth  may  declare 
the  most  successful  warnings  to  be  useless  because  he  might  have 
predicted  just  as  well  the  bad  weather,  and  so  on.  A  strict  proof  of 
the  practical  worth  of  weather  predictions  and  storm  warnings  is  im- 
possible, but  the  general  impression  of  competent  persons  must  be 
considered  conclusive,  and  in  this  combined  impression  the  fulfillment 
of  the  prophecy  counts  for  only  one,  though  perhaps  the  most  im- 
portant, of  many  circumstances. 

If  we  ask  ourselves  whether  the  great  working  experience  which 
has  been  gained  in  weather  predictions  during  twenty  years  bears  a 
proportionate  relation  to  the  results  obtained,  we  must  decidedly  say 
no.  Among  the  people  there  is  a  widespread  belief  that  the  predictor, 
by  a  strict  and  thorough  verification  of  the  prediction  made  by  him, 
must  make  great  progress  in  his  judgment  and  experience.  Were  this 
so,  then  the  verifications  would  be  a  duty  and  worthy  of  the  attention 
of  the  meteorologists  to  whom  the  task  of  issuing  predictions  falls. 
Really,  this  task  is,  as  anyone  who  has  prosecuted  it  long  will  admit, 
on  the  whole  a  very  thankless  one,  and  the  time  which  is  expended 
on  it  can  be  much  better  employed  upon  meteorological  investiga- 
tions in  statistical  meteorology  upon  which  the  predictions  rest.  If 
one  will  study  critically  the  prediction  service,  the  investigations 
should  at  least  be  as  thorough  and  carried  out  according  to  as  strict 
methods  as  at  the  Seeioarte,  A  report  to  the  public  should,  in  this 
3 


34  CHICAGO    METEOKOLOGICAL    CONGRESS. 

case,  be  as  free  as  possible  from  numerical  data,  because  figures  on 
this  subject  are  generally  misunderstood  and  really  carry  only  prac- 
tical convictions  in  certain  directions  and  only  to  specialists.  For 
such  a  report,  a  statement,  as  direct  and  as  free  from  excuses  as  pos- 
sible, with  concrete  examples  and  the  opinion  of  specialists,  is  the 
most  convincing  and  suitable. 


9.— PRESENT    CONDITION    OF    THE    WEATHER    SERVICE- 
PROPOSITIONS    FOR    ITS    IMPROVEMENT. 
Prof.  Dr.  W.  J.  van  Bebber. 

In  the  states  in  which  weather  telegraphy  has  been  used  in  connec- 
tion with  weather  forecasts,  either  for  agriculture  or  navigation,  the 
experience  has  been  generally  that  the  views  on  the  value  of  forecasts 
have  been  partly  overstated  and  partly  understated,  and  that  the 
hopes  which  the  weather  service  first  inspired  have  not  been  fulfilled. 
The  reason  for  this  lies  in  the  fact  that  our  knowledge  of  the  causes 
of  meteorological  phenomena  is  so  meager  that  the  practical  weather 
prediction  is  always  accompanied  by  frequent  and  great  failure, 
which  jeopardize  more  or  less  its  usefulness,  that  the  progress  of  prac- 
tical meteorology  is  uncommonly  slow,  and  scarcely  noticeable,  and, 
finally,  that  the  knowledge  of  meteorology  generally,  and  especially 
of  the  principles  underlying  prediction,  is  so  slight  that  such  influ- 
ences as  the  moon,  have,  even  with  learned  people,  equal  or  greater 
value  than  the  prediction  issued  by  scientific  institutions. 

It  is  incontestably  true,  that  the  predictions  of  the  institutes  really 
have  a  basis  which  is  capable  of  further  development,  and  that 
already  in  the  present  state  of  our  knowledge  of  atmospheric  phe- 
nomena and  their  changes,  they  may  be  useful  for  practical  vocations, 
provided  that  all  available  means  shall  be  used  in  their  issue  and 
distribution,  and  that  the  public  understand  how  to  estimate  their 
worth. 

On  account  of  the  great  practical  meaning  of  the  forecasts  which 
increases  with  their  accuracy  as  well  as  with  the  extension  of  the 
interval  of  time  covered,  it  appears  our  duty  to  strengthen  and  to 
spread  the  fundamental  principles  in  order  to  accomplish  what  is 
possible  and  to  meet  the  wants  of  the  public  in  every  way. 

It  seems  difficult  to  put  together  the  success  which  has  been 
attained  in  the  several  states  in  order  to  have  an  adequate  survey  of 
the  utility  of  the  weather  service  in  these  states.  True,  figures  show- 
ing the  percentage  of  success  have  been  published  by  the  various 
Institutes,  but  these  have  for  the  estimation  of  the  real  worth  and 
utility  of  weather  prediction  but  very  little  value,  since  in  the  veri- 
fication a  series  of  circumstances  must  be  considered  which  influence 
the  final  result  greatly.     Chief  among  these  are  the  probability  of 


THE   WEATHER   SERVICE.  36 

the  occurrence  of  a  weather  phenomenon,  or  chance,  also  the  persist- 
ent tendency  of  the  weather,  and  finally,  the  greater  or  less  use  which 
can  be  derived  from  the  forecast.  So  long  as  all  these  points  do  not 
find  recognition  in  the  verification,  the  percentages  of  success,  no 
matter  how  scientific  and  rigorous  the  verifications  may  be,  are  only 
of  secondary  importance,  and  can  not,  as  may  easily  be  shown,  be 
regarded  as  proper  criteria  for  the  success  or  failure  of  the  predic- 
tion. But,  in  the  efforts  to  take  account  of  all  these  circumstances 
we  come  to  the  difficulty,  which  appears  the  more  insurmountable 
and  the  greater,  that  much  must  always  be  left  to  arbitrary  decision. 

Upon  these  points  a  detailed  report  of  Prof.  Dr.  Koppen  is  pre- 
sented to  the  Congress,  so  that  further  discussion  is  unnecessary.^ 

The  best,  and  up  to  now,  the  only  correct  and  definite  scale  for 
the  utility  of  prediction  is  the  judgment  of  the  public  and  of  that  por- 
tion of  the  public  which  is  most  interested  in  the  predictions,  that  is 
to  say,  the  coast  inhabitants  and  the  agriculturists,  who,  from  their 
vocations,  are  most  dependent  upon  wind  and  weather.  As  regards 
the  first  class,  opinions  have  been  given  in  the  United  States,  by 
the  London  Meteorological  Office,  and  by  the  Deutsche  Seewarte. 
According  to  these  the  coast  dwellers  regard  the  storm  warnings,  in 
spite  of  the  frequent  failures,  as  a  desirable  arrangement.  As  a  fur- 
ther confirmation  of  the  utility  of  the  storm  warnings  I  would  add 
the  fact  that  on  the  German  coast  the  Provincial  authorities  and 
some  private  persons  have  erected  and  maintained  signal  stations  at 
their  own  cost,  where  those  of  the  Government  were  not  sufficient. 

The  judgment  of  the  public  on  weather  predictions  for  agricultural 
and  industrial  purposes  differs  generally  so  much  that  it  appears  impos- 
sible at  present  to  draw  valid  conclusions  as  to  the  value  of  the  same ; 
however,  I  have  always  had  the  experience,  as  is  the  case  elsewhere, 
that  those  persons  who  have  a  direct  interest  in  the  predictions  place 
a  greater  value  upon  them  than  those  who  regard  the  thing  as  more 
indifferent  to  their  professions. 

On  the  whole,  it  can  be  affirmed  that  even  in  the  present  state  of 
weather  prediction  great  use  can  be  derived  for  practical  life,  so  that 
the  practice  of  it  by  Institutions  ought  not  to  be  given  up  or  cur- 
tailed. Therefore  it  appears  a  pressing  necessity  to  employ  all  suit- 
able means  to  advance  weather  prophecy,  such  as  (relating  to  weather 
telegraphy)  the  speedy  collection  and  distribution  of  the  reports 
and  (regarding  prediction)  the  application  of  p,ccumulated  experience 
which  can  add  to  the  progress  of  the  service,  that  is  to  say,  the  exten- 
sion of  the  predictions. 

^  See  Section  I,  p.  30.  See,  also,  Van  Bebber:  "Die  Ergebnisse  der  Wetterprog- 
nosen,"  MonatshericM  der  Deutschen  Seewarte,  1886 +.  "Ergebnisse  der  Sturm- 
warnungen,"  ib.,  1889  +,  and  Das  Wetter,  1889,  p.  268.  Monatliclie  Uebersicht  der 
Wittei-ung,  Hapaburg,  188?.     Monat&bericht  der  Seewarte,  Hamburg,  1889. 


36  CHICAGO    METEOROLOGICAL   CONGRESS. 

The  greatest,  and  also  the  best  organized,  system  of  weather  teleg- 
raphy is  in  the  United  States,  so  that  we  may  take  this  as  a  model 
for  the  other  countries.  In  Europe  there  must  be  radical  reforms, 
the  most  pressing  of  which  we  will  briefly,  but  emphatically,  mention  : 
Of  the  greatest  importance  is  the  acceleration  of  the  telegraphic 
service,  both  for  the  incoming  and  outgoing  telegrams,  and  upon  an 
international  basis.  For  this  purpose  the  introduction  of  a  circuit 
system  (as  is  used  in  the  United  States  and  latterly  for  other  purposes 
in  Germany)  appears  necessary.  It  would  suffice,  if,  immediately 
after  the  observation,  the  lines  should  be  placed  at  the  disposal  of 
the  Central  Institutes  for  one-half  to  one  hour,  during  which  time 
they  could  be  placed  in  possession  of  the  united  telegraphic  material. 
This  telegraphic  matter,  including  the  number  of  stations  and  the 
scope  of  the  data,  must  of  course  be  reduced  as  much  as  possible. 
With  this  the  introduction  of  simultaneous  (world)  time  is  necessary. 
The  advantages  and  disadvantages  as  regards  local  time  would  seem 
to  counterbalance  one  another. 

It  is  greatly  to  be  deplored  that  in  Europe,  although  it  is  recog- 
nized as  a  necessity,  uniform  hours  of  observation  can  not  be  agreed 
upon.     On  this  point  the  Institutes  should  come  to  a  decision. 

As  soon  as  the  data  are  collated  they  should  be  sent  to  a  number 
of  secondary  stations  so  that  within  a  few  hours  after  the  working  up 
of  the  observations  the  deduced  synopsis  and  predictions  can  be 
given  to  the  public.  A  suitable  remuneration  for  the  trouble  of  the 
observers  is  desirable. 

More  frequent  information,  at  least  three  times  a  day,  as  is  now 
done  at  many  Institutes,  increases  greatly  the  efficiency  of  the  weather 
service,  as  well  as  more  frequent  issue  of  predictions  when  it  suits  the 
requirements  of  the  public,  for  which  a  principal  hour  can  be  easily 
agreed  upon  by  the  Institutions.  The  idea  first  suggested  by  Buys- 
Ballot  to  connect  the  registering  apparatus  of  the  chief  station  con- 
tinually or  occasionally,  so  that  at  any  time  the  course  of  the  distant 
weather  elements  may  be  known  (tele-meteorology)  was  nothing  more 
than  a  dream  of  the  meteorologist  which  should  operate  for  a  short 
time  over  a  small  region.  And  yet  this  idea  seems  very  useful  for 
the  purposes  of  weather  forecasts,  and  especially  for  storm  warnings, 
so  that  from  its  moderate  cost  it  is  to  be  recommended  for  introduc- 
tion over  limited  areas,  as  I  have  already  shown.  If  the  chief  tele- 
graphic lines,  which  at  certain  hours,  especially  during  the  night,  are 
not  used,  could  be  arranged  for  tele-meteorology,  the  changes  of  the 
weather  elements  at  a  serieS  of  distant  stations  might  be  registered 
continually  or  intermittently  at  the  principal  stations. 

The  principles  which  in  our  region  are  used  for  the  making  of  fore- 
casts,. I  have  given  in  my  book  on  "Weather  Predictions,"  and  the 
opinion  expressed  is  that  the  fundamental  principles  are  the  same 


THE    WEATHER    SERVICE.  37 

everywhere.  In  the  present  state  of  the  science  it  appears  advisable 
to  advance  further  in  the  beaten  track  and  thereby  to  fix  and  extend 
the  basis. 

In  weather  prediction  the  distribution  of  pressure  and  its  manifold 
changes  are  of  greatest  importance,  that  is  to  say,  the  position,  the 
progress,  and  especially  the  changes  of  the  high  and  low  pressure 
areas.  The  last  show,  indeed,  characteristic  weather  conditions,  but 
these  are  greatly  modified  by  secondary  formations.  These  seconda- 
ries, which  have  a  much  more  regular  course  than  is  generally  sup- 
posed, merit  chiefly  our  attention,  since  their  influence  on  wind  and 
weather  is  of  decided  importance.  These  depressions  often  make  the 
carefully  prepared  predictions,  especially  storm  warnings,  fail  totally. 
Not  infrequently  they  cause  sudden  increase  of  wind,  a  change  in  its 
direction,  and  consequently  great  temperature  fluctuation  and  heavy 
precipitation,  and  in  summer  widespread  squalls  or  tornadoes.  On 
the  south  side  of  depressions  they  mostly  move  quickly  over  large 
extents  of  country;  sometimes,  moreover,  they  change  their  posi- 
tion but  little  and  resolve  themselves  into  an  extensive  region  of  low 
pressure,  or  fill  up.  This  is  the  reason  why  forecasting  is  associated 
with  so  many  difficulties  which  can  be  the  more  slowly  overcome 
because  the  preceding  occurrences  in  the  upper  air,  which,  without 
doubt,  have  the  closest  relation  to  those  on  the  surface,  are  almost 
entirely  unknown  to  us. 

To  what  meteorological  elements  shall  the  predictions  refer  ? 
Evidently  such  as  will  meet  the  demands  of  the  public — that  is  to  say 
(certain  conditions  excluded),  for  the  coast  people,  first,  wind  direc- 
tion and  velocity,  then  fog,  and  finally  the  other  elements ;  for  the 
agriculturists,  first,  precipitation,  next  temperature,  then  cloudiness 
and  wind. 

On  account  of  the  uncertainty  of  the  predictions,  details  should  be 
avoided  (which  are  often  given)  and  the  doubtful  should  be  more  re- 
pressed, especially  when  the  weather  situation  is  uncertain,  and  then 
the  most  important  elements  for  practical  purposes  should  be  dwelt 
on.  If  the  weather  situation  is  uncertain  this  should  be  stated  in  the 
prediction.  The  intensity  of  the  precipitation  is  very  difficult  to 
predict  and  can  be  done  only  in  certain  cases.  Denmark  has  to  my 
knowledge  the  simplest  predictions  for  agricultural  purposes  which 
only  state  whether  the  weather  for  the  following  day  will  be  dry, 
changeable,  or  rainy.  This  method  has  much  value,  it  seems  to  me, 
as  at  the  same  time  temperature  and  other  predictions  are  given 
when  they  seem  necessary  to  the  public  and  when  the  weather  situa- 
tion warrants  them. 

Long  experience  has  shown  that  the  predictions  which  have  the 
greatest  chance  of  success  are  those  which  have  the  closest  relation  to 
the  pressure  distribution,  such  as  the  direction  and  strength  of  the 


38  CHICAGO    METEOROLOGICAL   CONGRESS. 

wind ;  next,  those  which  depend  chiefly  on  the  wind  and  air  trans- 
portation, that  is  to  say,  the  temperature  phenomena  and  to  some 
degree  the  hygrometric  conditions  of  the  air.  According  to  this,  the 
prediction  of  clouds,  fog,  and  precipitation  is  always  more  difficult 
than  those  of  wind  and  temperature,  because  here,  besides  the  air 
movement,  other  factors  occur,  such  as  vertical  air  currents,  topo- 
graphical conditions,  etc.  From  what  has  been  said  it  follows  that 
the  results  of  the  storm  warnings  are  more  favorable  than  those  of 
the  agricultural  predictions,  although  the  percentage  of  success  seems 
to  prove  the  contrary.  The  reason  is  that  with  cloud,  fog,  precipita- 
tion and  in  less  degree  with  temperature,  not  only  chance  but  also 
the  persistent  tendency  play  an  important  role,  while  the  probability 
of  the  occurrence  of  a  storm  and  of  its  continuance  is  relatively  ex- 
tremely small,  so  that  even  percentages  of  success  which  hardly  reach 
50  ought  not  to  be  regarded  as  unfavorable,  though  predictions  of  the 
severity  of  the  storm  and  the  timeliness  of  the  warnings  are  of  much 
importance.  Evidently  predictions  which  rest  only  on  chance  or  on 
persistence  are  absurd ;  for  it  is  the  changes  of  weather  mainly  which 
must  be  predicted. 

Snowdrifts  occur  most  frequently  in  certain  types  of  weather,  and 
therefore,  the  communication  of  such  warnings  to  the  railroads  ought 
to  be  valuable.  Such  an  arrangement  exists  in  Russia  since  1891, 
and  the  results  have  not  been  unfavorable,  seeing  that  most  railroads 
regard  the  warnings  as  useful. 

That  predictions  of  the  changes  of  the  height  of  rivers  (floods) 
can  well  be  made  has  been  sufficiently  proved  by  the  experience  in 
the  United  States,  in  Bohemia,  and  in  other  countries. 

The  value  of  the  predictions,  aside  from  their  trustworthiness,  is 
also  dependent  upon  the  length  of  time  which  they  cover.  Up  to 
now  most  of  the  Institutes  issue  forecasts  only  for  the  following 
twenty-four  hours  or  for  the  ensuing  civil  day.  The  shortness  of 
this  time  does  not  correspond  to  practical  needs ;  often  the  predic- 
tion only  comes  to  the  public  on  the  day  for  which  it  applies.  A 
prediction  for  two,  three,  or  more  days  in  advance,  if  the  accuracy 
was  not  very  much  less  than  that  for  one  issued  one  day  ahead, 
would  be  of  the  greatest  value.  It  is  only  a  question  whether  in  the 
present  state  of  practical  weather  knowledge  such  a  step  is  desirable. 
Everywhere  experience  has  showii  that  in  general  over  large  regions 
the  same  weather  condition  lasts  a  considerable  time  and  then, 
finally,  either  slowly  or  suddenly,  is  transformed  into  another  more 
or  less  opposed ;  so  that,  for  example,  periods  of  dull,  rainy,  and 
stormy  weather  are  followed  by  clear,  dry,  and  calm  w^eather  with 
which  the  temperature  phenomena,  chiefly  dependent  upon  the  air 
movement,  on  the  season,  and  on  the  cloudiness,  have  to  do.  If  a 
typical  weather  condition  is  formed,  it  appears  that  a  long-range 


THE   WEATHER   SERVICE.  39 

prediction  can  safely  be  made,  and  it  only  remains  to  announce  an 
alteration  in  the  character  of  the  weather  or  a  change  of  weather. 
In  long-range  predictions  two  cases  occur,  viz. :  (1)  To  determine 
the  degree  of  probability  that  the  weather  character  will  last  a  longer 
or  shorter  time,  and  (2)  to  predict  this  change.  The  last  is  by  far 
the  most  difficult,  and  we  ought  not  to  forget  that  a  critical  point  of 
weather  prophecy  lies  here — an  uncertainty  which  it  must  be  the  aim 
of  practical  meteorology  to  remove,  but  whose  full  accomplishment 
can  not  be  expected  at  present. 

In  weather  forecasting,  the  position  of  the  country  relative  to  its 
system  of  stations  and  to  the  track  of  low  pressure  areas  is  important. 
The  European  countries  lying  to  the  westward,  such  as  the  Iberian 
Peninsula,  France,  Great  Britain,  and  Norway,  are  hardly  in  a 
position  to  issue  long-range  predictions  whose  success  would  be 
comparable  with  those  issued  by  the  countries  lying  to  the  eastward. 
Towards  the  south  of  the  globe  the  changes  in  general  weather 
character  become  less,  but,  on  the  other  hand,  local  phenomena  are 
more  marked.  In  northern  Europe  typical  weather  phenomena  are 
the  rule,  but  the  propagation  and  the  changes  of  the  depressions 
(secondaries)  show  many  changes  in  which  the  disturbances  coming 
from  northwest  and  west  present  the  greatest  anomalies. 

It  would  be  of  the  greatest  advantage  for  long-range  forecasts  if 
the  weather  service  stretched  westward  into  the  ocean,  both  by  weather 
telegrams  from  the  Faroe  Islands,  Greenland,  and  the  Azores  and  by 
telegraphic  reports  in  the  eastern  regions  of  the  North  Atlantic  Ocean, 
from  the  ports  of  the  trans-Atlantic  steamers,  which  often  outstrip 
in  speed  the  depressions.  Thereby  would  the  costly  trans-Atlantic 
telegrams  received  from  Washington,  concerning  the  weather  in  the 
west  of  the  North  Atlantic,  have  more  value. 

The  situation  of  the  eastern  United  States  is  favorable  for  weather 
predictions  for  some  time  ahead,  although  the  movement  of  the 
maxima  and  minima  is  much  quicker  than  in  Europe,  and  conse- 
quently the  changeableness  of  the  weather  is  much  greater  than  in 
Europe,  and  the  more  so,  since  the  northern  and  southern  air  cur- 
rents present  such  extreme  contrasts  as  occur  nowhere  else  over  so 
extensive  a  region. 

In  spite  of  all  these  ideas,  long-range  weather  predictions  can  only, 
according  to  my  mind,  be  recommended  when  they  are  issued  with 
the  necessary  prudence  and  when  they  are  made  with  a  strong  proba- 
bility of  success.  In  conjunction  with  these  the  customary  forecast 
for  the  following  day  should  be  maintained,  as  is  done.at  the  Weather 
Bureau  at  Washington.  Recently,  the  Seewarte  has  given  in  its 
weather  summary  opinions  of  the  probable  course  of  the  weather  for 
an  indeterminate  time,  as  soon  as  the  weather  situation  warranted  it, 
and  with  good   results.      Latterly,  also,  in    Switzerland    long-range 


40  CHICAGO    METEOROLOGICAL    CONGRESS. 

predictions  have  been  made  (but  not  published),  and  not  without 
success. 

The  efficiency  of  the  weather  prediction  can  be  increased  in  a  high 
degree  by  teaching  the  public  the  ruling  principles  and  to  connect 
the  local  observations,  made  with  or  without  instruments,  with  the 
general  atmospheric  conditions,  so  that  in  certain  cases  it  can  judge 
why  the  actual  course  of  the  weather  agrees  or  does  not  agree  with 
the  predicted,  and,  under  certain  conditions,  how  far  the  forecasts 
must  be  modified.  Local  observations  in  combination  with  the  gen- 
eral weather  situation  give  results  which  are  not  to  be  undervalued, 
since  in  most  cases  they  take  into  account  the  changes  which  the 
weather  conditions  undergo  in  a  certain  place.  In  order  to  enable 
the  public  to  follow  the  weather  conditions  day  by  day,  the  circula- 
tion of  newspaper  weather  charts  appears  very  desirable,  and  here  I 
may  cite  the  efforts  of  the  Berlin  Weather  Bureau,  which,  increasing 
year  by  year,  at  present  furnishes  weather  maps  to  seven  of  the  great 
daily  papers,  besides  those  posted  on  the  numerous  Urania  columns. 
On  the  other  hand,  it  is  to  be  desired  that  the  chart  issued  by  the 
Institute  should  be  sold  at  a  moderate  price,  or,  if  possible,  distrib- 
uted gratis.  The  free  distribution  of  the  forecast  telegram  is  also  to 
be  recommended. 

Unfortunately,  we  have  to  admit  that  such  a  desirable  understand- 
ing of  practical  weather  lore  is  unknown  to  the  public,  as  well  as  to 
learned  persons,  and  we  must  further  admit  that  the  blame  rests  partly 
upon  the  fact  that  most  meteorologists  consider  it  sufficient  to  pre- 
sent to  the  public  the  relatively  few  principal  doctrines  of  practical 
meteorology,  and  do  not  exj)ose  superstitious  views  or  limit  their 
belief.  I  have  already  stated  the  fact  that  the  weather  bulletins  and 
charts  issued  by  the  meteorological  institutes,  and  partly  also  the 
predictions,  have  only  a  small  practical  value  if  their  comprehension 
be  wanting.  It  is  the  duty  of  every  meteorologist,  so  far  as  he  can 
to  strive  in  this  direction,  not  only  on  the  ground  of  utility  but  also 
for  the  advancement  of  science. 

Finally,  the  accuracy  of  weather  forecasts  can  be  greatly  increased  if 
the  specific  cases  be  compared  with  similar  previous  cases.  Therefore 
it  is  very  desirable  to  arrange  the  weather  charts  of  the  previous  years 
according  to  general  methods,  such  as  storm  tracks,  in  order  that 
these  comparisons  may  be  at  once  instituted.  Thereby  our  experience 
and  also  our  skill  in  making  predictions  will  be  greatly  advanced; 
and  we  are  soon  able,  at  the  sight  of  any  weather  chart,  to  form  a  judg- 
ment as  to  the.probable  sequence  of  the  weather  conditions.  Such  a 
procedure  must  be  attended  with  good  results,  as  my  own  experience 
has  shown.  It  appears  desirable  that  for  vast  regions,  such  as  North 
America  and  Europe,  with  the  neighboring  oceans,  a  numerous  col- 
lection of  systematically  arranged  charts  should  be  published  which 


THE    WEATHER    SERVICE.  41 

would  permit  the  course  of  the  elements  to  be  traced  from  the  pre- 
ceding to  the  following  day.  Such  an  atlas  would  be  of  great  value, 
not  alone  for  the  Institute  but  also  for  the  public,  which  is  now  often 
able  to  form  an  idea  of  the  prevailing  weather  conditions  from  the 
newspaper  weather  charts.  A  special  atlas  for  the  agricultural  fore- 
casts and  one  for  the  storm  warnings  appears  in  any  case  necessary. 

Since  the  Vienna  Congress  and  the  Utrecht  Conference  there  has 
been  little  accomplished  by  the  meteorological  congresses  and  con- 
ferences ;  therefore  it  is  to  be  hoped  that  at  the  present  Congress  the 
most  pressing  needs  will  be  satisfied. 

APPENDICES. 

[Extracts  from  letters  received  by  Dr.  Van  Bebber  from  rei)resentatives  of  weather 
services  in  reply  to  questions  relating  to  the  present  condition  of  the  weather  service 
in  their  respective  countries.] 

I. — Meteorological  Service,  Canada. 

1.  The  degree  of  accuracy  of  our  forecasts  of  temperature,  rain,  and 

wind  for  one,  tioo,  or  three  days  in  advance. 

2.  As  to  the  principles  on  which  the  forecasts  depend,  and  the  character 

of  the  weather  loe  are  able  to  predict. 

3.  As  to  the  advisability  of  predicting  rain,  and  the  extent  to  which  loe 

shoxdd  predict  temperature  or  other  changes  viewed  from  the  stand- 
point of  what  it  is  possible  to  predict  with  a  fair  degree  of  suc- 
cess, and  what  it  is  the  public  cares  to  know  ? 

1.  The  ordinary  forecasts  of  the  Canadian  Service  are  issued  from 
the  Central  Office  at  Toronto  at  11  p.  m.  daily,  and  are  distributed 
by  the  various  telegraph  companies  to  nearly  every  telegraph  office 
in  the  older  provinces,  and  in  Manitoba.  The  forecast  is  for  the 
twenty-four  hours  from  8  a.  m.  of  the  morning  after  issue  to  8  a.  m. 
of  the  following  day,  i.  e.,  practically  a  thirty-six-hour  prediction ;  a 
supplementary  forecast  is  made  at  10  a.  m.  each  day,  modifying,  if 
necessary,  that  of  the  previous  night,  but  is  not  very  generally  util- 
ized, as  the  Toronto  and  Montreal  evening  papers  and  the  Toronto 
Board  of  Trade  are  the  only  means  by  which  the  public  can  obtain 
them,  unless  by  direct  inquiry  from  Toronto  Observatory  or  the  tele- 
graph offices  at  Toronto. 

In  making  the  ordinary  forecasts  the  predicting  officer  at  Toronto 
endeavors  to  give  the  public  as  accurate  an  outline  as  possible  of  the 
weather  during  the  prescribed  period ;  he  is  not  bound  by  any  hard 
and  fast  rule  to  predict  for  every  suljject  that  may  be  included  in  the 
general  word  "  weather,"  such  as  wind  velocity  and  direction,  temper- 
ature, rain,  and  weather  in  the  more  restricted  meteorological  sense, 
although  in  every  instance  he  feels  bound,  even  when  grave  diffi- 
culties are  to  be  contended  against,  to  forecast  as  to  the  probability 


42  CHICAGO    METEOROLOGICAL   CONGRESS. 

of  rain  for  at  least  that  portion  of  the  prescribed  period  which  lies 
between  8  a.  m.  and  11  p.  m.  of  the  next  day. 

As  a  rule,  a  prediction  is  made  for  wind  velocity  and  direction, 
weather,  temperature,  and  rainfall,  both  as  regards  time  and  amount 
for  each  of  the  various  districts  into  which  the  Dominion  has  been 
divided.  Each  morning  the  forecasts  of  the  previous  day  are  com- 
pared with  the  actual  weather,  and  each  item  entered  in  a  table  under 
the  headings  "number  of  predictions,"  "number  fully  verified," 
"  number  partly  verified,"  "  number  not  verified."  At  the  end  of  the 
month,  when  more  numerous  reports  have  been  received,  these  figures 
are  checked,  and  if  necessary  changes  made,  and  a  percentage  struck 
by  taking  half  those  "  partly  verified  "  as  verified,  and  the  other  half 
as  not  verified.  In  every  instance  rain  is  counted  as  a  prediction, 
absence  of  rain  when  predicted  being  counted  a  failure,  as  is  also 
rain  when  no  prediction  of  it  has  been  made.  The  tables  on  pp.  43 
and  44  show  the  degree  of  success  with  which  we  meet  in  forecasting 
rain,  wind,  and  temperature,  and  that,  roughly  speaking,  we  are  about 
as  likely  to  fall  into  error  by  predicting  it  too  often,  as  by  not  predict- 
ing it  often  enough. 

It  sometimes  happens,  in  the  more  settled  weather,  that  the  pre- 
dicting officer  feels  very  sure  of  his  ground  and  makes  a  two  or  three 
day  prediction,  but  no  separate  percentage  of  verification  of  such 
predictions  has  been  kept.  Telegraphic  and  telephonic  inquiries  for 
extended  predictions  are  being  continually  received  at  the  observa- 
tory, and  the  fact  that  certain  firms,  of  various  descriptions,  have  for 
years  made  a  practice  of  asking  for  extended  forecasts,  and  by  word 
of  mouth  and  by  letter,  acknowledged  their  usefulness,  proves  that 
such  forecasts  are,  to  say  the  least,  fairly  successful. 

2.  The  forecasts  as  issued  from  Toronto  depend  altogether  on  a 
knowledge  obtained  from  practice  and  study  of  the  movements  of 
areas  of  high  and  low  pressure  on  this  continent,  and  the  weather 
which,  under  various  circumstances,  accompanies  these  areas,  taking 
fully  into  account  in  predicting  for  certain  districts  the  influence 
that  winds  of  different  directions  and  increased  or  diminished  mois- 
ture will  have  in  the  various  cases.  The  predicting  ofiicer  has  by 
experience  learned  much  as  to  the  influence  that  areas  of  high  pres- 
sure and  of  low  pressure  will  probably  have  on  each  other  as  regards 
development  or  dispersion  and  rate  of  movement,  and  makes  his  pre- 
dictions on  the  basis  that  the  pressure  changes  will  be  as  he  antici- 
pates. It  is  not  an  uncommon  thing  for  him,  when  an  abnormal 
movement  of  a  cyclone  has  occurred,  to  base  a  prediction  on  the 
assumption  that  such  movement  was  either  directly  or  indirectly 
caused  by  another  cyclone  beyond  the  region  of  observation,  for 
instance  at  sea,  and  in  this  manner  many  storms  on  our  seaboard 
have  been  foreseen,  the  existence  of  which  would  otherwise  not  have 
been  suspected. 


THE   WEATHER    SERVICE. 


43 


Although,  up  to  the  present  time,  very  little  use  has  been  made  of 
the  kind  and  direction  of  upper  clouds,  it  is  full  well  recognized  that 
a  greater  knowledge  of  the  relationship  of  the  upper  currents  to 
cyclones  and  anti-cyclones  may  ultimately  lead  to  more  exact  and 
extended  forecasts.  Even  at  present  weather  prognostics  dependent 
on  clouds  are  not  by  any  means  ignored,  as  in  cases  of  doubt  as  to  the 
hovering  or  change  in  direction  of  movement  of  a  cyclone,  such  indi- 
cations are  at  times  of  decided  value. 

3.  What  is  it  the  public  cares  to  know?  The  mariner  wants  to 
know,  just  prior  to  sailing,  the  force  and  direction  of  wind  he  may 
expect  during  periods  varying  from  a  few  hours  to  several  days ;  fish- 
ermen are  ordinarily  satisfied  with  twenty-four-hour  forecasts;  the 
agriculturist  wants  to  know  generally  as  to  the  likelihood  of  rain 
during  harvest  time,  and,  in  the  case  of  the  Northwest  farmer,  the 
likelihood  of  early  frosts ;  the  shipper  of  perishable  goods  wants  to 
know  the  best  time  to  ship  in  order  to  escape  severe  frost ;  the  gen- 
eral public  wants  to  know  the  general  character  of  the  weather  to  be 
expected  on  any  given  day  and  the  day  following. 

Our  ordinary  forecast  percentages  show  that  we  are  able  to  predict 
direction  and  velocity  of  wind  with  tolerable  accuracy  for  a  period  of 
thirty-six  hours,  and,  at  times,  for  a  longer  period,  and  we  have  a  per- 
centage of  verification  of  storm  warnings  of  84  per  cent ;  therefore, 
the  meteorological  service  is  of  benefit  to  the  mariner. 

Our  percentages  show  a  verification  of  74  per  cent  for  thirty-six- 
hour  forecasts  of  rain.  We  know  that  the  public  generally,  and  the 
agriculturist  in  particular,  consult  the  probabilities  and  believe  in 
them ;  therefore,  it  is  obviously  advisable  to  predict  rain. 

Our  percentages  show  a  verification  of  84  per  cent  for  temperature 
for  thirty-six-hour  forecasts,  and  during  winter  the  service  is  con- 
tinually consulted  as  to  cold  waves,  etc.  This  shows  that  temperature 
predictions  are  possible,  and  are  appreciated  by  that  portion  of  the 
public  more  directly  interested. — B.  F.  Stupart,  Predicting  Officer. 

Table  showing  percentage  of  verification  of  predictions  of  rain,  temperature,  and 

wind  velocity. 


Predictions. 


>, 

£• 

8 

03 

3 

03 

a 

L4 

t>^ 

a 

>. 

3 

0 

> 

S 

0 

=8 

IP 

s 

<; 

s 

s 
1-^ 

S 

< 

0 
0 

Z 

152 

120 

130 

128 

131 

I2S 

ISS 

131 

137 

136 

122 

142 

108 

92 

»3 

79 

81 

7» 

108 

94 

103 

82 

69 

104 

32 

12 

20 

17 

25 

18 

20 

16 

15 

25 

27 

17 

133 

n5 

132 

153 

147 

161 

159 

156 

160 

151 

152 

159 

7« 

73 

79 

qo 

95 

110 

113 

93 

104 

105 

112 

102 

26 

lb 

30 

30 

20 

26 

24 

32 

14 

20 

17 

28 

I  S3 

148 

164 

I.S4 

152 

ISS 

181 

i.SS 

155 

155 

155 

166 

86 

q8 

lO.S 

Iiq 

98 

96 

128 

94 

100 

98 

92 

110 

47 

31 

26 

24 

33 

30 

30 

24 

23 

28 

32 

32 

Precipitation. 
1890— 

Number 

Fully  verified 

Partly  verified 

1891— 

Number 

Fully  verified 

Partly  verified 

1892— 

Number 

Fully  verified 

Partly  verified 


1,607 

1,081 

244 

1.778 

1. 154 

283 

1.893 

1,224 

360 


44 


CHICAGO    METEOROLOGICAL   CONGRESS. 


Table  showing  percentage  of  verification,  etc. — Continued. 


Predictions. 


Peecipitation— Continued. 

Total  for  three  years- 
Number  438  383 

Fully  verified !  272  263 

Partly  verified 105  59 

Total  percentage  for  three  years 

■  Temperature. 
1890 — 

Number 

Fully  verified 

Partly  verified 

1891— 

Number 

Fully  verified 

Partly  verified 

1892— 

Number 

Fully  verified 

Partly  verified 

Total  for  three  years- 
Number  

Fully  verified 

Partly  verified 


Total  percentage  for  three  years 
Wind  velocity. 


Number 

Fully  verified  . 
Partly  verified. 


Number 

Fully  verified  .... 
Partly  verified 

1892— 

Number 

Fully  verified 

Partly  verified 

Total  for  three  years- 
Number  

Fully  verified  ... . 
Partly  verified.... 


Total  percentage  for  three  years 


1781  166 
III    120 

37 1    18 


426  435  430 
267!  288|  274. 
76     71     78 


145    147 

124'  108 

14 


80 


242    229 

158,  152 
42     53 


59 


256  252 
193'  195 
46     38 


493  442 
349;  2S1 
74     72 


153    141 
126;  120 


lOIj 

78, 

17 

277, 
228 

3i| 


38    107 

271  77 
8     16 

53I  80 
29  46 
i6     18 


442  429;  467 
285  273;  316 
73     76     77 


136  146 
115  124 
13 


242   268 

158!  189 
38     50 


5.278 
3.459 

887 

73-9 


1,450 

1,186 

133 

1,702 

1.354 

216 

1,737 

1.347 

222 

4,889 

3,887 

571 

83-7 


945 
682 
154 

957 
698 
142 

819 

533 
157 

2,721 

1,913 

453 

78.6 


Rain  predictions  for  June. 


188S 
1889 
1890 
1891 
1892 


Number  of 
predic- 
tions. 


Fully  ver- 
ified. 


43 


Partly  ver- 
ified. 


Not  ver- 
ified. 


Percentage 
fully  ver- 
ified. 


81.8 
58.3 
64-3 
60.0 
69.2 


66.2 


Percentage 
fully  and 
partly  ver- 
ified. 


91.0 
83-3 
85-7 
80.0 
92-3 


86.2 


Days  of  no  rain  predictions. 


Year. 

Number  of 
days. 

Fully  ver- 
ified. 

Partly  ver- 
ified. 

Not  ver- 
ified. 

Percentage 
fully  ver- 
ified. 

Percentage 
fully  and 
partly  ver- 
ified. 

1888 

15 
13 

II 

H 
13 

12 
6 

8 
9 
6 

2 
3 
2 
I 
3 

I 
4 
I 

I 
4 

80.0 
46.2 

72-7 
81.8 
46.2 

93-3 
69.2 
91.0 
91.0 
69.2 

1880 

1890 

l8qi 

i8q2 

63 

41 

II 

II 

65.1 

82.5 

THE    WEATHER    SERVICE.  45 

II. — Danish  Meteorological  Institute. 

COPENHAGEN. 

We  issue  only  storm  warnings.  For  nautical  purposes,  signals  are 
displayed  in  Helsingor  for  the  wind  conditions  in  the  Cattegat, 
which  signals  ca,n  be  seen  by  ships  about  to  sail.  The  daily  weather 
review  is  also  posted  in  each  port. 

Our  daily  weather  map  is  based  on  the  morning  telegrams  from 
three  English,  three  Norwegian,  seven  German,  four  Swedish,  two 
Russian,  nine  French,  and  eleven  Danish  stations.  Every  day  a  sum- 
mary of  the  weather  situation  is  given,  as  well  as  the  weather  forecast. 
The  forecast  is  only  expressed  in  general  terms,  and  we  take  no  pains 
to  name  each  element  in  our  forecast.  Hektographic  copies  are 
posted  in  various  parts  of  the  city  as  well  as  at  the  port.  The  review 
and  forecast  are  telegraphed  at  2  p.  m.  to  all  telegraphic  stations  and 
then  publicly  displayed.  During  the  months  of  June  to  September 
an  afternoon  service  is  maintained.  The  review  and  forecast  are 
based  on  meteorological  dispatches  from  three  English,  one  Norwe- 
gian, two  German,  one  Swedish,  and  four  Danish  stations.  The  fore- 
cast relates  mainly  to  precipitation,  and  the  following  terms  are 
used:  "clear  weather;"  "generally  clear  weather;"  "changeable 
weather,"  and  "  rainy  weather."  The  forecast  is  telegraphed  at  5  p. 
m.  to  all  the  telegraph  stations.  At  many  places  the  forecast  is 
transmitted  from  the  nearest  telegraph  office  to  the  neighborhood  by 
optical  signals. — Adam  Paulsen,  Director. 

III. — Norwegian  Meteorological  Institute. 

CHRISTIANIA. 

We  receive  telegrams  from  Norway,  Sweden,  Denmark,  the  British 
Islands,  France,  North  Germany,  and  Russia.  Besides  synoptic 
charts  of  the  preceding  evening  and  the  morning,  we  construct  charts 
of  change  of  pressure  from  evening  to  morning,  change  of  tempera- 
ture in  the  last  twenty-four  hours  (8  a.  m.),  deviation  of  the  tem- 
perature at  8  a.  m.  from  the  normal,  and  temperature  distribution  at 
8  a,  m.  Only  the  synoptic  charts  are  posted.  For  the  greater  part  of 
the  year  our  predictions  (extending  from  noon  to  noon)  are  only 
published  in  Christiania.  In  all  months  they  apply  only  for  Chris- 
tiania  and  neighborhood.  The  area  is  more  limited  in  winter 
than  in  summer.  In  winter  we  predict,  as  far  as  we  can,  temperature, 
precipitation,  and  wind.  In  the  summer  months  (June-September) 
the  predictions,  intended  for  farmers,  give  precipitation.  These  are 
telegraphed  and  telephoned  southward  to  Skien,  northward  to  Hamar^ 
westward  to  Randsfjord,  eastward  to  the  boundary  of  the  kingdom. 
We  have  attained  90  to  92  per  cent  of  success. 

Storm  warnings  are  only  occasionally  sent  to  the  coast  when  the 


46  CHICAGO    METEOROLOGICAL    CONGRESS. 

weather  signs  in  Scotland  at  8  a.  m.  have  begun  to  give  warning. 
Storm  warnings  are  not  sent  farther  north  than  Bodo.  The  shore 
community  is  satisfied.  We  have  received  latterly  pecuniary  aid 
from  the  Storthing  in  order  to  undertake  special  weather  studies  with 
the  intention  of  establishing  local  systems  of  weather  warnings  with 
local  centers  in  Bergen,  Throndheim,  and  at  the  great  fisheries 
(Lofoten,  for  example)  under  the  direction  of  local  meteorologists  as 
directors.  The  principles  according  to  which  we  issue  warnings  are 
hard  to  analyze — scientific  instruction,  local  experience,  imagination. 
It  is  quite  as  much  an  art  as  a  science  which  one  practices. — Dr.  H. 
Mohn,  Director. 

IV. — Russia:  Central  Physical  Obseevatory. 

SAINT    PETERSBURG. 

I  send  you  reports  of  the  observatory  for  the  years  1886-1891,  as 
well  as  the  report  concerning  the  service  of  the  forecasts  of  snow- 
drifts on  the  railroads.  With  the  permission  of  the  director.  Dr.  H. 
Wild,  I  add  an  extract  from  the  report  for  1892.  The  rules  which 
we  follow  for  weather  predictions  are  about  the  same  as  stated  in 
your  (Dr.  Van  Bebber's)  excellent  book,  which  is  used  as  a  text  book 
in  the  forecast  department. 

Since  July,  1892,  after  previous  trials,  the  general  weather  predic- 
tions have  been  subjected  to  regular  tests,  as  published  in  the  bul- 
letin. The  predictions  for  the  districts  of  European  Russia  (compare 
map  in  supplement  to  Daily  Bulletin)  have  been  separated  and  veri- 
fied for  the  four  elements  of  precipitation,  cloudiness,  temperature, 
and  wind.  For  each  of  the  elements  three  grades  were  distinguished, 
a  hrgh,  a  mean,  and  a  fair  grade.  The  predictions  were  considered  as 
successful  when,  at  the  majority  of  stations  in  the  given  district,  the 
predicted  phenomena  were  observed  in  the  jjredicted  degree.  As 
partly  successful  were  taken  those  predictions  for  which  the  phe- 
nomena did  not  show  the  indicated  grade  but  the  next  one  to  it.  As 
unsuccessful  predictions  were  regarded  those  for  which  the  opposite 
of  the  predictions  was  observed. 

Uxample. 


Prediction. 

Observation. 

Verification. 

r  Thick  clouds 

Successful. 

Thick  clouds 

\  Cloudy  

Partly  successful. 

[Fair 

In  the  final  verification  of  the  degree  of  success  of  the  prediction 
the  number  of  partly  verified  predictions  is  distributed,  half  to  the 
successful  and  half  to  the  unsuccessful  prediction. 


THE    WEATHER   SERVICE. 


47 


The  exact  determination  of  the  notation,  the  sub-division  of  the 
districts,  and  the  choice  of  the  grade  for  the  characteristic  weather 
demand,  however,  special  meteorological  researches;  consequently, 
the  verification  adopted  for  1892  is  to  be  regarded  as  a  first  attempt 
to  determine  the  proper  criteria. 

The  results  of  the  verification  are  given  in  percentages  in  the  fol- 
lowing table : 
Verification  of  the  general  weather  predictions  for  six  months  (July-December)  of  1892. 


Predictions. 

Successful. 

Unsuccessful. 

Per  cent. 

8o.6 
77-2 
82.5 
80.8 

Per  cent 

19.4. 
22.8 

17-5 
19.2 

85.6 
79.0 
80.9 

14.4 
21.0 
19. 1 

75-8 
85.6 
80.2 
79-5 

24.2 
14.4 
19.8 
20.5 

81.0 

19.0 

Districts: 

Northwestern  Russia 

Western  Russia 

Central  Russia 

Northeastern  Russia. 

Eastern  Russia 

Southeastern  Russia . 
Southwestern  Russia. 

Elements: 

Precipitation 

Clouainess 

Temperature 

Wind 

Mean 


Besides  the  general  weather  predictions  which  are  published  daily 
in  the  bulletin,  more  than  one  hundred  and  fifty  replies  are  given 
by  the  department  to  private  inquiries  (mostly  from  Perm  and  Nizh- 
nee-Novgorod )  concerning  the  expected  weather.  Besides  this,  dur- 
ing three  months  (in  summer  and  autumn)  daily  weather  predictions 
are  made  for  Pawlowsk. 

From  the  preceding  table  it  is  evident  that  the  percentages  of  the 
successful  predictions  for  the  different  districts  of  European  Russia 
are  dissimilar,  being  larger  in  the  east  and  smaller  in  the  west.  This 
difference  is  more  marked  in  the  comparison  of  the  results  of  pre- 
dictions for  single  places.  The  number  of  successful  predictions  for 
those  stations  lying  in  the  east  (Perm,  Nizhnee-Novgorod,  Saratov, 
etc.)  is  80  to  81  per  cent,  while  in  Pawlowsk  it  only  reaches  63  to  64 
per  cent. 

In  the  supplement  we  reproduce  three  letters  ^  from  Mr.  Panaew  and 
one  from  Mr.  Batjuschkow,  in  which  the  writers  express  their  thanks 
for  the  predictions  sent  them.  From  these  letters  it  appears  that  our 
predictions  are  practically  useful ;  this  result  is  for  us  the  more  satis- 
factory since  it  is  not  based  on  single  chance  forecasts,  but  upon  a 
whole  systematic  series  of  predictions,  of  which  naturally  a  certain 
percentage  may  be  bad.  It  should  here  be  remarked  that  both  the 
above-mentioned    gentlemen    were    subscribers    to   the   telegraphic 


^  These  letters  were  not  received  by  me. — Editor. 


48  CHICAGO    METEOROLOGICAL    CONGRESS. 

« 
weather  predictions  and  in  consequence  paid  for  each  one  a  tax  of  50 
kopecks  besides  the  usual  tax.     In  both  letters  the  wish  is  expressed 
that  further  progress  may  be  made. 

Storm  learnings  for  the  Baltic  and  for  the  Black  and  Azof  Seas  in  1892. 
[The  general  results,  expressed  in  percentages,  are  for  all  districts.] 


Warnings. 


Verified 

Partly  verified 

Late 

Not  verified  ... 


Baltic. 


63 


Black. 


65 


The  percentage  of  storms  which  were  not  predicted,  whose  force 
exceeded  that  indicated  by  one  ball,  was,  for  the  Baltic  Sea,  10  per 
cent  (1891,  13  per  cent) ;  for  the  Black  Sea,  19  per  cent  (1891,  23  per 
cent).  If  we  combine  the  verified  and  partly  verified  warnings  the 
result  of  the  successful  warnings  for  1892  is  as  follows :  Baltic  Sea, 
85  per  cent  (1891,  76  per  cent) ;  Black  Sea,  76  per  cent  (1891,  69  per 
cent). — Ch.  Rykatchcw. 

V. — The  Weather  Service  in  Austria. 

VIENNA. 

In  Austria  the  issue  of  a  telegraphic  weather  report  was  begun 
January  1,  1877.  This  service  is  carried  on  by  three  ofiicials  of  the 
"  Section  for  Weather  Telegraphy,"  whose  office  since  the  year  1879 
is  in  the  center  of  the  city  in  the  building  of  the  Imperial  Academy 
of  Science.  The  telegraphic  material  has  increased  notably  since 
1877.  At  present  there  are  received  daily  weather  reports  from 
thirty-six  Austro-Hungarian  and  from  sixty-six  foreign  stations. 
These  are  dispatched  in  twelve  combination  telegrams  to  158  domestic 
and  foreign  stations.  The  monthly  subscription  price  for  the  weather 
report  is  1  fl.,  50  kr.  The  weather  report  goes  to  the  printer  not  later 
than  3  o'clock,  and  is  sent  out  regularly  before  5  o'clock.  At  the 
present  time  there  are  ninety-nine  subscribers  to  the  weather  report ; 
the  number  of  free,  exchange,  and  obligatory  copies  amounts  to  eighty. 
Besides  the  printed  weather  report,  there  have  been  sent  since  1877 
daily  prediction  telegrams  which  go  chiefly  to  the  landed  proprietors, 
health  resorts,  and  the  larger  provincial  papers.  Since  the  year  1884 
the  prediction  telegrams  have  been  in  cipher,  whereby  the  subscrip- 
tion price  has  been  reduced  50  per  cent  to  its  present  price  of  5  fl.  per 
month.     The  telegrams  are  issued  generally  between  1  and  1.30  p.  m. 

The  success  of  the  predictions  is,  on  the  whole,  satisfactory,  aver- 
aging 85  per  cent.  The  subscribers  to  the  prediction  telegrams 
have  varied  since  1878  from  fifty  to  eighty-three.  As  regards  the 
relation  of  the  public  and  their  interest  in  the  weather  to  the  predic- 
tion service,  the  journalists  hold  an  important  place.    In  Vienna  all 


THE    WEATHER    SERVICE.  ^        49 

the  great  newspapers  are  forced  by  their  readers  and  correspondents, 
both  in  the  morning  and  evening  editions,  to  print  the  telegraphic 
weather  reports  with  the  predictions.  When,  from  lack  of  space  or 
other  reasons,  the  weather  report  does  not  appear,  complaints  come 
at  once  to  the  publishers.  The  confidence  in  the  weather  predictions 
manifests  itself  most  strongly  in  the  fact  that  not  only  the  Viennese, 
but  also  the  great  proprietors  in  the  provinces  take  pains  to  procure 
the  predictions. — Dr.  J.  Hann,  Director  Central  Bureau  for  Meteorology 
and  Terrestrial  Magnetism. 

VI. — HuNGAEiAN  Meteorological  and  Magnetic  Bureau, 

Budapest. 

Weather  predictions  were  issued  in  1881  by  direction  of  the  Min- 
ister of  Agriculture,  at  that  time  Baron  Kemsny,  by  Dr.  Szentgyorgyi 
Weisz,  who,  however,  was  independent  of  the  Meteorological  Insti- 
tute. The  dissemination  of  the  forecasts  was  accomplished  through 
the  newspapers ;  the  telegraphic  dispatches  were  insufficient  and 
after  eight  years'  continuance  this  arrangement  was  given  up. 

In  the  year  1888  the  task  of  making  weather  predictions  was  en- 
trusted to  the  Meteorological  Institute,  but  still,  this  service,  in  the 
too  narrow  limits  to  which  it  was  confined  by  the  previous  organiza- 
tion, could  get  no  firm  hold. 

A  noteworthy  advance  in  this  field  can  be  recorded  when  I  took 
the  direction  of  the  Central  Bureau.  On  June  15,  1891,  our  first  syn- 
optic charts  appeared,  whose  issue  was  facilitated  by  a  subvention 
from  the  Minister  of  Agriculture.  The  forecasts  were  publicly 
posted  in  Budapest  and  their  circulation  was  confined  to  the  daily 
newspapers.  On  account  of  the  great  importance  of  the  predictions 
in  an  agricultural  state  like  Hungary,  a  quicker  and  more  general 
dissemination  of  the  forecasts  was  desirable.  The  present  Minister 
of  Agriculture,  Count  Andreas  Bethlen,  manifests  a  lively  interest 
in  the  matter  and,  acting  on  my  suggestion,  has  succeeded  in  enlist- 
ing the  Ministry  of  Commerce.  The  creation  of  such  a  method  of 
forecast  dissemination  as  exists  in  Hungary,  according  to  my  knowl- 
edge, has  not  come  about  in  any  other  European  country. 

There  was  inaugurated,  primarily,  a  general  official  method  of  dis- 
tributing the  predictions  in  the  interest  of  the  farming  community. 
Accordingly,  on  August  1,  1892,  the  first  forecast  dispatch  (in  cipher) 
was  issued  as  an  appendix  to  the  official  "circular  dispatch,"  which 
contains  the  quotations  of  the  Budapest  merchandise  and  grain  ex- 
changes, and  by  way  of  experiment  this  forecast  dispatch  was  sent  to 
one  hundred  and  thirty  telegraph  offices  for  official  distribution  to 
the  public.  Each  of  these  telegraph  operators  received,  also,  a  suit- 
able bulletin  board  on  which  the  data  and  the  announcements  form- 
ing the  forecasts  were  to  be  hung.  There  belong  with  each  board 
4 


50  CHICAGO    METEOROLOGICAL   CONGRESS. 

twelve  small  tablets  for  the  different  mouths,  thirty-one  tablets 
(bearing  the  numbers  1-31)  for  the  days,  and  thirty-one  for  the  pre- 
dictions. On  the  last  are,  together  with  the  cipher,  also  the  an- 
nouncements belonging  to  each.  The  telegraph  operator  is  thus  re- 
lieved of  all  trouble  of  translation ;  his  task  consists  only  in  taking 
from  a  box  that  tablet  which  bears  the  cipher  of  the  forecast  dis- 
patch just  received  and  in  hanging  it  up. 

This  method  of  spreading  the  information  deserves  to  be  mentioned 
because  it  is  a  free  one  and  is  solely  for  the  benefit  of  the  agricultural 
community.  Much  public  interest  is  everywhere  manifested,  and  the 
agricultural  societies  in  many  counties  have  applied  to  the  Govern- 
ment for  an  increase  in  the  number  of  telegraph  operators  who  have 
been  entrusted  with  the  receipt  and  the  puljlication  of  the  forecast 
dispatches,  so  that  at  present  one  hundred  and  thirty  officials  have 
been  appointed,  and  after  May  1,  1893,  two  hundred  and  sixty  tele- 
graph offices  will  serve  to  disseminate  the  predictions.  Further,  for 
remote  places  and  for  Puszten  (inns  in  out-of-the-way  localities)  an 
optical  method  of  signaling  is  projected,  so  that  by  displaying  dif- 
ferent colored  flags,  baskets,  and  cones  (made  of  osier)  the  forecasts 
will  be  made  known.  On  my  estate  in  O'Gyalla  and  on  that  of  the 
Minister  in  Bethlen  this  scheme  is  already  in  operation. 

The  forecasts  relate,  exclusively,  to  the  conditions  which  are  of 
interest  to  farmers,  that  is  to  say,  especially  to  precipitation  and 
temperature .  and,  incidentally,  to  cloudiness.  Storm  warnings  are 
not  issued.  The  forecasts  apply  for  the  following  twenty-four  hours, 
but  in  consequence  of  the  importance  which  a  forecast  of  the  weather 
for  two  days  ahead  possesses  for  agriculture,  in  certain  cases  of 
weather  stability  one  is  undertaken  for  two  days  with  the  announce- 
ment, "weather  conditions  persistent  (w),"  as  well  as,  when  the 
weather  condition  admits,  a  change  for  the  second  day  is  indicated 
by  "later  precipitation  (x),"  or  "later  clearing  (z)."  The  varia- 
bility of  the  climatic  conditions  requires  that  from  the  extent  of 
Hungary,  in  special  cases,  the  rain  probability  should  only  relate  to 
certain  regions,  which  is  indicated  by  the  announcements  "precipi- 
tation in  the  west  (1),"  "precipitation  in  the  south  (j),"  etc.  The 
forecast  dispatches  are  sent  until  3  o'clock  each  afternoon  from  the 
Institute  to  the  telegraphic  centers. 

At  present  the  Meteorological  Institute  is  hoping  for  a  reorgan- 
ization which  will  create  a  special  section  for  "  Weather  Telegraphy 
and  Forecasts."  It  will  only  then  be  possible  to  study  the  weather 
conditions  in  detail  from  the  point  of  view  of  forecasts,  and  to  pre- 
pare the  needed  statistical  data. 

Regarding  the  success  of  the  forecast  dispatches,  I  can  only  now 
cite  the  computed  results  which  relate  to  the  quarter  August-October, 
1892.     The  figures  are  obtained   by  a  comparison  of   the   forecasts 


THE    WEATHER    SERVICE.  51 

with  the  records,  at  the  hours  7,  2,  and  9,  of  twelve  uniformly-dis- 
tributed meteorological  observing  stations.  These  forecasts  were 
verified  in  the  above-mentioned  quarter,  for  precipitation,  84.7 ;  tem- 
perature, 76.1 ;  and  cloudiness,  86.2  per  cent.  With  the  establish- 
ment of  a  special  section  it  is  the  intention  to  develop  further 
the  whole  forecasting  service,  of  which  I  may  speak  more  at  length 
later. — Dr.  N.  von  Konkoly,  Director. 

VII. — The  Weather  Service  in  the  Netherlands. 

UTRECHT. 

Installation. — At  Utrecht,  after  the  arrival  of  the  dispatches  from 
the  Netherlands,  about  10  to  11  a.  m.,  the  report  is  placarded  and 
published  in  the  morning  edition  of  the  local  newspapers  which 
appear  about  1  p.  m.  Beneath  the  report  is  entered  the  greatest 
barometric  deviation  which  is  (graphically)  represented  on  the 
aeroklinoskop  (c/.,  Invoering  en  Verklaring,  translated  by  Dr.  Jelinek 
with  the  title  The  Aeroklinoskop).  In  the  afternoon,  about  3  p.  m., 
the  weather  chart,  manifolded  by  the  hektograph  process,  is  issued, 
beneath  which  is  a  summary  of  the  greatest  barometric  deviation  at 
8  a.  m.  and  12.30  p.  m.,  and  a  weather  prediction  for  the  twenty-four 
hours  following  the  observation.  The  weather  charts  published  at 
Utrecht  are  sent  elsewhere  on  payment  of  postage. 

Results. — The  results  of  the  predictions  are  seldom  expressed  by 
figures.  Results  of  the  storm  warnings,  which  are  based  on  the  dif- 
ferences of  the  barometric  deviations,  are  published  annually  in  the 
Niederldndischen  Meteor ologischen  Annalen.  The  results  of  the  two  last 
years  are  that  60  per  cent  of  the  storm  warnings  were  not  verified. 

Presentation  to  the  public. — The  organization  of  the  weather  service, 
which  is  essentially  represented  by  the  Telegraphisch  Weerbericht  ten 
dienste  van  den  Landbouio  and  which  dates  from  the  close  of  1882,  was 
for  several  years  unfavorably  regarded  by  the  public,  just  as  the 
storm  warnings  were  for  the  fifteen  or  twenty  years  preceding.  There 
followed  a  period,  which  still  continues,  when  the  public,  took  little 
or  no  notice  of  the  weather  reports.  Only  about  1889  was  there 
shown  a  greater  interest  by  the  public  which  manifested  itself  in  the 
appearance  of  a  daily  weather  chart  in  two  newspapers,  the  first  and 
up  to  now  the  only  ones  in  the  Netherlands  to  publish  these  charts. 

The  degree  of  accuracy  in  predictions  of  temperature,  snow,  rain,  or 
wind,  tioo  or  three  days  in  advance.  What  principles  are  adopted  in  such 
predictions?  Utrecht  issues  a  definite  wind  prediction,  which  is 
founded  on  the  difference  of  the  barometric  deviation,  and  a  more  or 
less  detailed  weather  prediction  for  the  ensuing  twenty-four  hours. 
A  temperature  and  wind  prediction  is  seldom  made  for  the  second 
twenty-four  hours,  never  for  the  third,  and  never,  as  regards  rain,  for 
the  second  period.     These  predictions,  like  those  for  the  first  twenty- 


52  CHICAGO   METEOROLOGICAL   CONGRESS. 

four  hours,  are  based  on  the  determination  of  the  current  gradient 
(not  barometric  gradient)  of  the  air  in  a  vertical  and  horizontal  direc- 
tion, on  the  modifications  which  they  may  undergo  during  the  day, 
and  on  the  physical  changes  which  may  result. 

It  is  desired  chiefly  to  predict  those  weather  elements  which  are 
most  related  to  the  duration  of  the  prediction,  such  as  temperature 
and  rain,  for  example. 

Rain  prediction  is  the  most  important  for  the  public,  and  is  also 
the  most  uncertain ;  even  the  thunderstorm  prediction,  which  has 
even  more  value  and  also  is  the  surest,  has  often  only  a  local  verifi- 
cation.— Abridged  translation  by  Mr.  Engelenburg. 

AMSTEEDAM. 

The  weather  service  in  Amsterdam  furnishes  information  about  the 
weather  not  only  to  the  public  in  Amsterdam,  but  also  to  the  Staats- 
anzeiger  and  the  Harlemmer  Zeitung.  These  papers  receive  as  full  a 
summary  as  those  in  Amsterdam.  The  report  is  telegraphed  to  the 
Staatsanzeiger  each  noon,  while  the  Harlemmer  Zeitung  sends  for  it. 
The  latter  paper  wishes  no  tabular  data,  but  only  a  summary.  Be- 
sides, there  is  sent  to  other  places  in  the  Netherlands  a  weather  sum-  ■ 
mary,  with  a  wind  prediction  added  to  the  Telegraphisch  Weerbericht  ten 
dienste  van  den  Landbouw.  These  reports  are  published  by  harbor- 
masters, provincial  newspapers,  etc.  Finally,  in  many  places  in  Am- 
sterdam, and  also  in  Harlem  and  at  the  office  of  the  Harlemmer  Zei- 
tung, hektographic  weather  reports  are  posted. 

I  believe  the  value  of  the  Telegraphisch  Weerbericht  ten  dienste  van 
den  Landbouio  to  be  very  small.  A  mere  statement  that  "  a  depres- 
sion lies  northwest  and  far  off"  or  "a  high  pressure  area  northeast 
and  in  the  neighborhood"  is  incomprehensible  and  of  no  value  to 
the  public. 

The  abstracted  tables  containing  data  for  some  domestic  and  for- 
eign stations  may,  however,  be  useful,  but,  in  general,  I  do  not  think 
that  the  ordinary  newspaper  readers  care  much  for  the  report.  It  is 
otherwise  with  seaports,  where  great  differences  in  the  barometric  devi- 
ations may  serve  as  warnings  to  seamen.  This  branch  of  the  service 
should,  according  to  my  ideas,  be  better  supported.  The  aerokli- 
noskop,  which  is  set  up  in  some  places,  does  not  fulfill  the  want. 
To  the  ports  (especially  Delfzyl,  Nieuwe-Diep,  Ymuiden,  Zandvoort, 
Scheveningen,  Maassluis,  Vlaardingen,  Hellevoetsluis,  Brouwershaven, 
Vlissingen)  storm  signals,  analogous  to  those  of  the  Deutsche  Seewarte 
or  those  long  employed  on  the  English  coast,  should  be  supplied. 
The  aeroklinoskop  can  only  be  read  at  a  little  distance,  and  demands 
too  much  imagination  on  the  part  of  the  simple  fishermen  and  sea- 
men. 

The  reports  which  the  Amsterdamer  Zeitung,  the  Harlemmer  Zeitung, 


THE   WEATHER   SERVICE.  53 

and  the  Staatsanzeiger  receive  are  fully  appreciated  by  a  portion  of 
the  public,  really  more  than  the  editors  of  the  papers  realize.  The 
Harlemmer  Zeitung  shows  that  the  public  does  not  know  exactly 
for  how  long  the  prediction  applies,  since  a  great  part  of  its  readers 
believes  that  the  whole  of  the  next  day  is  included  in  the  prediction. 
In  Amsterdam  the  prediction  never  extends  more  than  twenty-four 
hours,  and  since  the  report  is  made  up  between  12  and  2  (including 
the  last  observation  at  12.30  p.  m.,  from  the  interior)  the  prediction  ex- 
tends from  noon  of  one  day  to  noon  of  the  next.  According  to  my 
ideas,  it  is  too  uncertain  to  make  predictions  for  two  or  three  times 
twenty-four  hours,  for  in  such  cases  the  disappointment  is  greater  and 
the  confidence  is  decreased.  For  inland  places  where  the  papers,  un- 
like the  Staatsanzeiger^  do  not  receive  a  full  report,  and  give  it  only  in 
the  evening  to  their  readers  (until  the  Telegraphisch  Weerhericht  ten 
dienste  van  den  Landbouiv  makes  way  for  a  better  arrangement),  the 
weather  reports,  consequently,  can  be  of  little  use. 

The  predictions,  as  they  are  now  carried  on  in  Amsterdam,  indi- 
cate :  Wind  direction,  and  in  the  case  of  great  barometric  differ- 
ences, wind  force ;  also  the  general  weather,  designated  as  follows, 
"good  weather,"  "tolerably  good  weather,"  "little  change,"  "change- 
able weather,"  "squally  weather,"  "boisterous  weather,"  etc.  When 
the  condition  of  the  depression  is  accompanied  by  a  strong  tendency 
to  rain  there  is  added  to  the  prediction  "  much  probability  of  rain," 
"rain  or  snow,"  etc.  Finally,  there  is  sometimes  hazarded,  as  regards 
temperature,  something  in  the  nature  of  a  conjecture  —  "warm 
weather,"  "cold  weather,"  "higher  temperature,"  "lower  tempera- 
ture." Since  the  rain  and  temperature  predictions  can  be  made  with 
much  less  certainty  than  those  for  wind  and  general  weather,  they 
are  not  usually  given  and  only  when -their  fulfillment  is  tolerably 
certain. 

Agriculture  should  derive  the  greatest  advantage  from  these  rain 
and  temperature  predictions,  and  therefore  it  is  my  opinion  that  agri- 
culture receives  no  material  advantage  from  the  weather  service. 
Navigation,  on  the  contrary,  which  is  chiefly  concerned  with  wind  and 
general  weather,  can  derive  much  benefit  from  the  weather  service, 
especially  when  storm  signals  can  be  given  the  ports.  I  would  men- 
tion that  in  Ymuiden  there  are  often  sent  to  war  and  sometimes  to 
merchant  vessels,  ready  to  leave,  a  complete  dispatch  containing  a  re- 
review  and  a  forecast.  Further,  according  to  my  idea,  by  the  em- 
ployment of  a  private  telephone  line  the  harbor  and  fishing  port  of 
Ymuiden  could  receive  much  better  information  than  it  does  now. 
Probably  Maassluis,  opposite  Rotterdam,  is  in  the  same  situation. 

The  wind  and  weather  predictions,  as  drawn  up  in  Amsterdam,  are 
based  on  the  general  situation  in  Europe  at  8  a.  m.,  and  on  the 
probable  changes  and  their  sequences,  for  which  the  Handbuch  der  aus- 


54  CHICAGO    METEOROLOGICAL    CONGRESS. 

itbenden  WitteruiKj.^kunde  of  Dr.  W.  J.  Van  Bebber,  and  more  recently 
the  Wettervorhersage  of  the  same  author,  are  used  as  guides. 

If  one  considers  that  in  the  Netherlands  only  once  in  twenty-four 
»  hours  a  review  of  the  situation  over  Europe  can  be  had,  and  in  Ger- 
many, for  example,  this  is  made  three  times  a  day,  it  appears  to 
me  that  the  result  of  the  predictions  in  Amsterdam  is  not  wholly 
unfavorable.  It  is  very  much  to  be  desired,  that  (for  example  at  1 
p.  m.)  some  dispatches  should  be  received  directly  from  England, 
France,  and  Germany  (for  example  six  or  eight)  and  immediately 
charted.  If  that  could  be  done,  the  value  of  the  prediction  would 
thereby  be  greatly  increased.  Nevertheless,  I  repeat,^  no  dispatch 
should  be  more  than  one  hour  late. 

In  brief,  my  opinion  is,  that  apart  from  some  progress  which  may 
still  be  made  in  meteorology  as  a  science,  it  is  very  desirable,  as  may 
now  be  done,  by  an  acceleration  of  the  dispatches  and  a  proper  means 
of  distributing  and  publishing  the  reports,  that  the  public  should 
derive  greater  advantage  from  the  reports  than  is  at  present  the 
case. — Abridged  translation  by  L.  Boosenburg. 

ROTTERDAM. 

The  weather  service  in  Rotterdam  is  confined  to  the  communication 
of  weather  reports  to  the  papers  published  in  Rotterdam  and  the  dis- 
tribution of  this  report  within  the  parish.  This  is  accomplished  by 
mere  mechanical  working  up  of  the  dispatches  received ;  it  seems  to 
me,  therefore,  that  a  central  bureau  can  hardly  be  spoken  of.  Predic- 
tions are  not  made  here,  unless  the  paragraph  which  follows  the 
barometric  deviations  from  the  normal  be  regarded  as  such,  for  ex- 
ample, the  paragraph  "indicates  a  .  .  .  .  wind,"  or  in  the  hektographic 
weather  reports  "  according  to.  the  Buys-Ballot  law,  there  should  be 
a  .  .  .  .  wind." 

I  have  left  these  expressions  because  it  is  difficult  to  give  a  full 
explanation  each  day,  but  I  do  not  consider  them  as  forecasts.  It  is 
only  the  statement  of  two  phenomena  between  which  there  exists  a 
certain  relation  without  our  being  able  to  say  in  general  that  one 
is  the  cause  and  the  other  the  consequence. 

The  value  of  weather  predictions  published  for  the  public  appears 
to  me  doubtful,  especially  because  to  the  forecasts  which  are  unsuc- 
cessful much  more  attention  is  paid  than  to  the  others. 

From*'private  telegrams,  especially  in  commercial  circles,  it  has 
often  been  shown  to  me  that  much  interest  attaches  to  weather 
reports  which  make  known  the  true  situation,  and  that  it  is  to  be 
regretted  that  our  reports  do  not  cover  a  larger  portion  of  Europe. 

The  method  of  procedure  here  is  as  follows :  At  noon,  the  Scheep- 
voort  newspaper  sends  for  a  list  of  the  reports  already  received.  This 
list  is  posted  outside  a  Avindow  of  the  newspaper  office  in  the  neighbor- 


THE    WEATHER    SERVICE.  55 

hood  of  the  Exchange.  At  certain  seasons,  dependent  on  the  sugar 
crop,  a  copy  of  this  is  posted  in  the  Exchange.  Between  2  and  3 
o'clock  a  complete  weather  chart  is  hektographed,  and  the  Scheep- 
voort  distributes  sixteen  copies  throughout  the  city,  which  are  acces- 
sible to  the  public  at  large,  and  are  also  posted  in  localities  where 
many  interested  persons  assemble,  as  for  example,  exchanges,  com- 
mercial clubs,  societies,  etc.,  for  the  benefit  of  navigation,  navigation 
schools,  trades  unions,  etc.  Further,  about  6  p.  m.,  there  appears  in 
the  Scheepvoort  a  small  map,  printed  by  the  Rung  system,  and  about 
5  o'clock  a  full  list  with  a  general  review  is  published  in  the  Neue 
Rotterdamcr  Zeitung.  This  paper,  also,  has  received  for  some  time 
past  a  graphic  representation,  in  a  form  devised  by  the  editors,  of  the 
highest  and  lowest  barometer  and  the  temperature  during  the  five 
preceding  days. 

The  great  expense  which  the  Scheepvoort  incurs,  as  well  as  the  large 
space  which  the  Neue  Rotterdamer  Zeitung,  from  interested  motives, 
devotes  to  this  matter,  and  the  questions  which  occasionally  reach 
me  through  the  editors  of  these  papers,  impress  me  with  the  fact  that 
they  count  among  their  readers  many  who  are  interested  in  this  sub- 
ject.— Abridged  translation  by  Arkenbout  Schokker. 

VIII. — London  Meteorological  Office. 

Dr.  Van  Bobber's  letter  asks  various  questions:  (1)  As  to  the 
degree  of  accuracy  in  our  forecasts  of  temperature,  rainfall,  wind,  etc., 
for  one,  two,  or  three  days  in  advance.  (2)  As  to  the  principles  on 
which  the  forecasts  depend,  and  the  character  of  the  weather  we  are 
able  to  predict.  (3)  As  to  the  advisability  of  predicting  rain,  and 
the  extent  to  which  we  should  predict  temperature  or  other  changes 
viewed  from  the  standpoint  of  "  what  it  is  possible  to  predict  with  a 
fair  degree  of  success  and  what  it  is  that  the  public  cares  to  know." 

The  following  replies  are  drawn  up,  not  exactly  in  the  order  in 
which  the  queries  are  put,  but  in  such  an  order  as  enables  me  to  re- 
ply more  clearly  and  briefly  than  I  could  otherwise  do. 

"  Forecasts  "  or  "  predictions  "  are  issued  by  this  office,  as  follows  : 

The  first  are  prepared  at  10.30  a.  m.,  and  issued  at  11  a.  m.  (Sun- 
days, Good  Fridays,  and  Christmas  days  excepted),  and  are  mainly 
dependent  on  the  observations  taken  at  8  a.  m.  daily  (see  copy  of  the 
Daily  Weather  Report)  and  relate  to  the  weather  to  be  expected  dur- 
ing the  twenty-four  hours  ending  at  noon  on  the  following  day.  They 
are  intended  chiefly  for  publication  in  the  Daily  Weather  Report, 
in  the  afternoon  newspapers,  and  for  exhibition  at  certain  positions 
in  the  city  and  west  end  of  London,  including  most  of  the  clubs. 

The  second  are  prepared  at  3.30  p.  m.  (Sundays,  Good  Fridays, 
and  Christmas  days  excepted)  from  2  p.  m.  observations,  and  made 
at  a  limited  number  of  stations,  as  supplementary  to  the  8  a.  m.  ob- 


66  CHICAGO    METEOROLOGICAL    CONGRESS. 

servations.  They  relate  to  the  weather  of  the  ensuing  civil  day. 
They  are  always  posted  at  the  door  of  the  office  for  inspection  by  the 
""public  and  during  the  hay  and  wheat  harvests  are  telegraphed  gra- 
tuitously to  a  selected  number  (about  twenty-eight)  of  agriculturists 
who  make  their  contents  known  as  widely  as  possible,  and  keep  a 
careful  check  on  their  accuracy. 

The  third  are  prepared  at  7.30  p.  m.,  daily,  and  are  issued  at  8.30 
p.  m.  These  also  relate  to  the  weather  of  the  ensuing  day,  and  are 
dependent  on  observations  made  at  6  p.  m.,  as  supplementary  to  those 
made  at  8  a.  m.  and  2  p.  m.  They  are  intended  mainly  for  publica- 
tion in  the  morning  newspapers  of  the  following  day. 

They  are,  therefore,  all  of  them,  for  a  period  of  rather  more  than 
twenty-four  hours  in  advance  of  the  time  of  issue,  and  are  utilized  in 
answering  inquiries  by  the  public  as  to  coming  weather. 

Special  "warnings"  as  to  the  advance  of  storms  are  sent  by  telegraph 
to  the  coasts  threatened,  whenever  the  indications  are  believed  to  be 
of  a  stormy  character.  These  may  be  sent  at  any  hour  between  9.30 
a.  m.  and  8  p.  m.,  and  are  made  known  by  the  hoisting  of  a  cone 
(point  up  for  northerly,  point  down  for  southerly  gales)  at  the  ports 
to  which  they  are  sent. 

In  the  forecasts  the  wind  (direction  and  force)  and  the  weather 
are  predicted  separately,  in  a  somewhat  general  lyanner,  as  the  dis- 
tricts for  which  they  are  prepared  cover  a  considerable  area.  In 
the  weather  portion  any  kind  of  weather  is  included,  if  it  is  likely  to 
be  a  prominent  feature,  but  at  present  hardly  any  attempt  has  been 
made  to  estimate  the  intensity  of  coming  rain — the  local  variations 
in  the  character  of  the  country  and  the  variations  in  intensity  of 
thundershowers  being  too  abrupt  to  make  minute  detail  desirable. 
Such  expressions,  however,  as  "rain  at  times — heavy  locally"  are 
employed  when  deemed  necessary. 

With  regard  to  changes  of  temperature,  two  distinct  classes  are 
kept  in  view,  (1)  those  of  a  general  and  (relatively)  of  a  permanent 
character  affecting  the  mean  temperature  of  the  approaching  period, 
and  referred  to  in  such  expressions  as  "colder,"  "much  colder," 
"warmer,"  "much  warmer,"  etc.,  and  (2)  those  of  a  diurnal  char- 
acter which,  in  such  periods  as  that  recently  experienced  over  our 
islands,  are  very  large,  and  are  referred  to  in  sentences  such  as  "  cold 
at  night,  warm  during  day."  No  attempt  has  been  made  hitherto  to 
check  the  accuracy  of  such  forecasts,  except  as  forming  part  of  the 
weather  portion  of  the  predictions,  but  it  is  believed  that  they  are  as 
good  as  those  for  any  of  the  other  features  included  in  the  forecasts. 

With  regard  to  the  success  which  has  attended  the  issue  of  the 
forecasts,  reference  may  be  made  to  many  distinct  sources :  ( 1 )  to 
the  official  checking  of  the  8.30  p.  m.  issue,  carried  on  in  this  office 
from  the  information  received  daily  by  wire.     The  results  of  this 


THE    WEATHER    SERVICE.  57 

checking  will  be  found  on  pp.  11  and  63  of  the  Rej)ort  of  the  Meteor- 
ological Council  for  year  ending  March,  1892,  and  are  very  fairly 
satisfactory.  (2)  To  a  similar  checking  of  the  3.30  p.  m.  forecasts, 
based  on  information  supplied  by  the  recipients  of  the  forecasts  (see 
same  report  pp.  12-13)  and  the  favorable  opinion  expressed  by  them 
in  their  letters  to  the  council ;  also,  to  the  fact  that  the  same 
gentlemen  are  glad,  year  after  year,  to  receive  the  forecasts,  to 
make  them  known,  and  to  keep  the  record  necessary  to  check  them. 
(3)  That  among  those  who  make  inquiry  privately,  the  same 
names  appear  regularly  in  successive  years,  whenever  the  informa- 
tion is  required,  although  a  fee  is  levied  for  it,  and  the  costs  of  trans- 
mission by  wire  (when  necessary)  are  paid  by  the  applicant.  (4)  To 
the  facts  that  (a)  the  National  Lifeboat  Institution  applied  recently 
to  have  the  forecasts  telegraphed  daily  to  the  officers  in  charge  at 
their  various  stations,  as  a  guide  to  them  in  their  duties  (a  request 
which  was  reluctantly  declined  only  because  the  cost  of  nearly 
£1,000  per  annum  was  more  than  the  Meteorological  Council  were 
able  to  meet),  and  (b)  that  the  Agricultural  Department  is  even 
now  endeavoring  to  make  arrangements  for  telegraphing  the  3.30  p. 
m.  forecasts  daily  to  all  agricultural  districts  during  harvest  time. 
(5)  That  the  authorities  at  Her  Majesty's  Dockyard,  Devonport, 
now  have  the  11  a.  m.  forecast  telegraphed  to  them  every  day  for 
guidance  in  sending  the  smaller  vessels  to  sea ;  and  that  Her  Majesty 
never  puts  to  sea  without  having  the  latest  forecast  transmitted  to 
her  by  wire.  (6)  That  the  newspapers  in  all  parts  of  the  kingdom 
have  not  only  published  the  forecasts  regularly  for  many  years,  but  in 
most  cases  pay  a  considerable  sum  for  cost  of  telegraphy,  when  the 
offices  are  too  far  distant  for  them  to  be  delivered  by  hand,  and  that 
The  Times  paid  £500  per  annum  for  the  exclusive  use  of  the  6  p.  m. 
forecasts,  and  subsequently  the  three  leading  London  papers  paid 
£900  per  annum  between  them  for  the  use  of  the  same  forecast  until 
the  Government  made  a  grant  to  defray  the  cost  and  make  the  infor- 
mation free  for  all  papers. 

With  regard  to  what  the  public  wish  to  know — they  would  un- 
doubtedly like  (a)  to  have  the  forecasts  issued  for  a  longer  j)eriod  in 
advance,  probably  for  seasons,  and  (h)  that  more  minute  detail 
should  be  observed  in  localizing  the  regions  likely  to  be  affected  by 
rain,  and  the  intensity  of  the  coming  fall.  At  present,  however,  it 
has  not  been  found  possible  to  gratify  these  wishes. 

This  brings  us  to  the  consideration  of  the  principles  adopted  in  pre- 
paring the  forecast,  and  the  line  of  work  or  study  which  promises  to 
increase  their  accuracy. 

With  regard  to  the  principles  adopted. — They  depend  mainly  upon  a 
recognition  of  the  well-known  characteristics  of  cyclonic  and  anti- 
cyclonic   systems,  primary,  secondary,   or  V-shaped,  and  upon  the 


58  CHICAGO    METEOROLOGICAL    CONGRESS. 

indications  afforded  by  the  three  daily  observations  as  to  their  move- 
ments and  the  questions  of  their  tendency  to  increase  or  decrease  in 
area  or  intensity.  The  general  distribution  of  pressure  (also  whether 
favorable  for  a  continuous  prevalence  of  cold  or  warm,  of  dry  or  wet, 
currents  of  air),  the  effects  of  such  currents  when  coming  from  off 
the  sea,  or  vice  versa,  the  relatively  rapid  motion  of  air  on  coasts 
when  compared  with  that  over  land,  and  the  variations  produced  by 
the  seasons  on  such  phenomena  are  all  carefully  thought  out  before 
preparing  the  forecasts  or  issuing  warnings,  besides  the  question 
whether  the  disturbances  are  of  a  "  thunderstorm  "  or  other  character, 

Willi  regard  to  the  line  of  work  or  study  most  likely  to  increase  the 
accuracy  of  the  predictions. — It  appears  probable  that  some  rearrange- 
ment of  the  districts  for  which  they  are  prepared,  the  separation  of 
coast  from  inland  parts  of  the  countries  and  of  the  west  from  the 
east  portions  of  the  Irish  districts,  is  desirable.  It  is  probable,  also, 
that  a  better  knowledge  of  the  upper  currents  of  the  air,  as  shown 
by  high  clouds,  is  necessary,  and  that  a  more  careful  study  of  the 
distribution  of  rainfall  under  varying  types  of  pressure  distribution 
and  at  different  seasons  of  the  year  (distinguishing  between  the 
various  classes  of  rains)  may  improve  the  forecasts  materially.  That 
every  effort  to  bring  about  such  an  improvement  is  desirable  must 
be  patent  to  all — sailors,  agriculturalists,  and  dwellers  in  towns  being 
all  interested  in  the  results. 

At  present  it  has  loeen  found  impossible  to  institute  seasonal  fore- 
casts with  any  reasonable  hope  of  success. — Frederic  Gaster,  Chief  of 
Forecast  Division. 

IX. — Berlin  Weather  Bureau.^ 

The  telegraphic  reports  are  received  from  the  Deutsche  Seewarte  in 
Hamburg,  and  during  the  past  year  another  telegram  has  been 
received  from  the  Royal  Bavarian  Central  Bureau,  containing  the 
reports  from  the  four  stations,  Ziirich,  Genoa,  Lugano,  and  Bozen, 
which  have  proved  very  useful. 

We  use  the  telegraphic  material  for  the  purpose  of  weather  fore- 
casting in  the  construction  of  isobars  and  isotherms,  and  for  about  a 
year  I  have  worked  with  an  assistant  (formerly  Dr.  Siihring,  now  Mr. 
Basilius)  iii  plotting  lines  of  equal  pressure  and  temperature  varia- 
tion in  twenty-four  hours.  The  method  of  verification  of  'our  fore- 
casts has  undergone  a  great  change  since  its  commencement  in  the 
spring  of  1884.  Together  with  the  systematic  verification  of  the  fore- 
cast, resolved  into  the  elements,  I  have  verified  also,  as  a  whole,  each 
forecast  according  to  the  Seewarte  method  (I,  entirely  successful,  up  to 

'  This  is  a  private  business  enterprise  with  its  headquarters  at  the  Agricultural  High 
School. — Editor. 


THE    WEATHER    SERVICE.  59 

V,  entirely  wrong),  in  which  I  have  endeavored  to  take  account  of  the 
views  of  the  local  public  as  much  as  possible,  and,  therefore,  to  give 
proportionately  more  weight  to  the  predictions  concerning  rain  and 
temperature  than  to  those  relating  to  cloudiness  and  wind  conditions. 
From  these  rules  the  following  percentages  of  success  were  obtained 

for  the  years  1885-'92  : 

I.  II.  III.  IV.  V.  Success. 

Winter  (Dec. -Feb.)...  18.2  48.1  29.6  4.1  0.0  81.1 

Spring 21.6  47.6  26.4  4.4  0.0  82.4 

Summer 15.3  49.1  29.7  -5.7  0.2  79.2 

Autumn 18.2  44.9  32.6  4.3  0.0  79.4 

Year 18.3  47.4  29.6  4.7  0.0  80.5 

The  most  favorable  month  was  April,  with  83.2  per  cent ;  the  most 
unfavorable,  October,  with  76.2 ;  and  next,  July,  with  78.9.  I  would 
here  remark  that  the  forecasts  are  issued  between  2.30  and  2.45  p.  m., 
and  apply  for  the  whole  of  the  following  calendar  day.  In  single 
years  an  increase  in  the  figures  denoting  success  is  not  evident,  and 
indeed  the  first  years  show  the  greatest  success,  viz.,  1885,  86.7  per 
cent,  and  1886,  84.6  per  cent.  This  arises,  however,  from  the  fact 
that  we  now  attempt  to  give  to  the  forecasts  a  more  definite  meaning, 
especially  to  emphasize  the  expected  weather  changes,  and  perhaps, 
also,  our  own  judgment  about  the  mistakes  has  become  harsher.  The 
continually  growing  interest  of  the  public  is  perhaps  best  shown  by 
the  results  outside  of  the  Bureau,  and  I  quote  below  the  number  of 
newspapers  to  which,  at  the  commencement  of  each  year,  we  were 
furnishing  weather  charts  and  forecasts : 

January  1.  1885.   1886.   1887.   1888.  1889.  1890.   1891.   1892.   1893. 

Forecasts 4        6         6  7  7        16        17       16        17 

Weather  cliarts ..  ..2444  6  67  7 

The  great  increase  from  1889  to  1890  is  partially  explained  by  the 
fact  that  Mr.  0.  Jesse,  who  up  to  that  time  had  made  forecasts  for 
four  local  papers,  gave  this  up  in  1889.  For  the  representation  of 
weather  charts  an  attempt  was  made  by  us  in  1885  to  stamp  them  on 
type  metal,  and  in  the  following  year  the  scheme  had  been  so  far 
perfected  that  it  was  applicable  to  stereotyped  papers,  among  which 
the  Berliner  Tageblatt,  which  had  already  for  many  years  printed 
weather  charts  by  an  etching  process,  adopted  ours ;  this  underwent 
a  further  improvement  in  1889  by  the  substitution  of  black  for  white 
figures  and  symbols.  Besides  this  newspaper  block,  which  is  ready 
at  2.30  p.  m.,  we  have  delivered  since  May,  1892,  daily,  except  Sun- 
day, at  4.15  o'clock,  hektographic  weather  charts  for  the  local 
"Urania  columns." 

I  will  now,  after  this  long  and  detailed  account  of  the  working  of  our 
weather  bureau,  state  briefly  the  experience  we  have  obtained  in  our 
efforts  to  improve  the  forecast  methods.  It  appears  to  me  that  the 
efforts  toward  longer  forecasts,  even  if  they  are  more  general,  promise 


60  CHICAGO    METEOROLOGICAL   CONGRESS. 

better  success  than  the  more  exact  ones  for  the  next  day.  In  addition 
to  the  thorough  researches  of  Van  Bebber,  upon  the  typical  tracks 
of  minima,  it  appears  to  me  that  a  more  detailed  investigation  of 
Teisserenc  de  Bort's  weather  types  would  be  very  profitable,  and  I 
believe  that,  to  the  knowledge  of  their  frequency,  duration,  change, 
sequence,  etc.,  my  weather  charts  might  contribute  somewhat. 

As  to  the  wish  of  the  public  respecting  the  forecasts  for  the  ensuing 
day,  it  has  been  my  experience  that  no  little  importance  is  attached 
to  the  explicitness  of  the  forecast.  So,  for  example,  it  will  not  suf- 
fice to  give  the  announcement  "  changeable  weather."  Here,  as  every- 
where, the  greatest  attention  must  be  given  to  the  precipitation  fore- 
cast, and  it  should  be  the  aim  gradually  to  separate  more  and  more 
the  local  from  the  general  rains,  and  in  summer  the  simple  "  tendency 
to  thunderstorms  "  might  be  replaced  by  a  greater  or  less  "  probability 
of  a  thunderstorm."  Perhaps,  a  systematic  investigation  of  the  vari- 
ation of  the  absolute  humidity,  for  which  I  have  for  several  years 
been  collecting  data,  might  contribute  something  to  this  question, 
although,  naturally  there  are  other  more  important  researches.  I 
believe  that  a  more  exact  knowledge  of  the  recent  precipitation  dis- 
tribution is  very  necessary,  for  which  reason  I  would  urge  that  in 
our  telegraphic  dispatches  the  tenths  of  degrees  of  temperature  be 
replaced  in  summer  by  the  amount  of  precipitation,  and  in  winter 
by  the  depth  of  snow.  But  the  subject  is  too  large  a  one  to  be 
exhausted  in  one  letter,  so  that  I  fear  I  have  already  entered  too 
much  into  details. — Dr.  E.  Less,  Director. 

X. — The  Forecast  Service  in  Switzerland. 

The  creation  of  a  daily  weather  forecast,  based  upon  synoptic 
meteorological  data,  was  first  undertaken  in  Switzerland  by  the 
undersigned,  in  the  summer  of  1878,  in  a  private  way.  In  the  year 
following  it  was  done  officially  by  direction  of  the  Swiss  Govern- 
ment ;  and  the  issue  of  a  daily  weather  bulletin  was  made  one  of  the 
duties  of  the  Swiss  Central  Meteorological  Institute,  established  in 
May,  1881. 

As  Switzerland  is  divided  into  several  (3-4)  districts  whose  cli- 
matic conditions  are  essentially  different  from  one  another,  it  was 
originally  planned  that  the  forecasts  should  be  made  at  several 
points,  based  upon  a  synoptic  summary  telegraphed  to  each  from  the 
central  office.  But  the  observatory  at  Berne  has  been  the  only  one 
to  undertake  the  issue  of  special  forecasts  for  the  surrounding  terri- 
tory ;  so  that,  as  a  matter  of  fact,  the  forecasts  of  the  central  institute 
at  Ziirich  have  continued  to  be  the  only  generally  distributed  prog- 
nostications. But  in  view  of  the  peculiar  geographical  position  of 
southwestern  Switzerland  (on  account  of  the  influence  of  the  lower 


THE    WEATHER    SERVICE.  61 

snow-valley),  the  Central  Institute  has  for  several  years  past  issued 
special  forecasts  for  that  district. 

The  necessity  for  a  forecast  service  for  that  jDart  of  Switzerland 
which  lies  beyond  the  Alps  (Tessin,  Engadin)  has  up  to  the  present 
been  less  urgent,  mainly  because  the  weather  of  that  district  is  much 
more  constant  than  on  this  side  of  the  Alps.  For  this  reason  no 
special  forecast  for  southern  Switzerland  is  as  yet  issued,  although  it 
would  be  less  difficult  than  for  the  northern  portion  of  the  country. 

The  distribution  of  the  forecasts  from  the  central  office  is  made 
partly  through  the  newspapers  and  partly  to  private  persons  by  tele- 
graph, for  which  latter  purpose  the  telegraph  authorities  have  granted 
a  considerable  reduction  in  rates.  The  forecasts  are  usually  given 
out  shortly  after  2  p.  m.,  and  have  been  made  only  for  the  day  fol- 
lowing. Recently,  however,  a  beginning  has  been  made  to  forecast 
for  longer  periods  than  twenty-four  hours,  and  not  without  success ; 
but  these  forecasts  are  not  yet  published. 

The  forecasts  embrace  temperature,  precipitation,  and  character  of 
weather.  Direction  and  force  of  wind  are  considered  only  when  steep 
gradients  exist,  since,  with  slight  gradients,  the  topographical  features 
ol  our  country  govern  the  local  wind  movements,  which  depend  almost 
entirely  upon  the  course  of  the  valleys  and  character  of  the  ground 
(lakes,  woods,  etc.),  and  their  prediction  for  each  little  district  would 
hardly  be  possible,  and  would  be  useless. 

The  forecasts  of  the  central  office  are  verified  both  at  the  office  itself 
and  by  the  observers  at  the  meteorological  stations  at  Aarau,  Lucerne, 
and  Neufchatel.  In  consequence  of  the  topographical  peculiarities 
already  referred  to,  the  verification  is  not  applied  to  each  separate 
meteorological  element,  but  is  made  according  to  three  classes,  wholly 
verified,  partly  verified,  and  not  verified,  according  as  to  whether  the 
forecast  was  correct  or  incorrect  with  reference  to  all  or  only  a  part 
of  the  meteorological  elements  considered  in  it.  The  average  found 
at  the  four  stations  is  72  per  cent  wholly  verified,  24  per  cent  partly 
verified,  and  4  per  cent  not  verified. 

The  attitude  of  the  public  with  reference  to  these  forecasts  is,  gen- 
erally speaking,  a  sympathetic  one.  That  the  institution  meets  with 
confidence  is  shown  by  the  very  numerous  special  inquiries  which 
reach  the  central  office  by  telegraph  from  far  and  near.  It  must  be 
stated,  though,  that  in  cases  of  total  failure  and  especially  when,  in 
place  of  the  expected  fine  weather  bad  weather  occurs,  the  criticism 
of  the  public  at  large  or  of  individuals  is  a  pretty  severe  one,  espe- 
cially in  comparison  with  that  which  is  in  some  cases  extended  to  the 
so-called  popular  weather  prophets.  Nor  can  it  be  denied  that  crit- 
icism is  occasionally  colored  by  a  malicious  joy  at  the  failure  of  the 
so-called  scientific  prophecy. 

The  needs  of  the  public,  with  reference  to  the  forecasts,  are  not  so 


62  CHICAGO    METEOROLOGICAL    CONGRESS. 

much  to  know  whether  there  will  be  a  slight  rise  or  fall  in  tempera- 
ture (leaving  out  entirely,  as  above  indicated,  wind  direction  and 
light  wind),  as  to  be  informed  of  the  general  character  of  the 
weather.  The  absolute  state  of  the  temperature  is  only  in  a  few  cases 
(in  spring)  of  special  interest,  and  the  same  may  be  said  as  regards 
the  amount  of  rainfall  (when  there  is  danger  of  floods). 

In  most  cases  only  the  general  character  of  the  weather  is  under 
consideration,  and  consequently  the  greatest  importance  is  attached 
to  its  correct  determination.  Sudden  changes,  especially,  demand 
the  most  attentive  consideration.  The  so-called  local  influences  pecu- 
liar to  our  mountain  country  are  important  factors  in  this  connec- 
tion. Of  very  great  importance  is  the  distribution  of  the  atmos- 
pheric pressure  on  both  sides  of  the  Alps.  It  depends  upon  this  dis- 
tribution whether  or  not  the  influence  of  a  depression  moving  from 
north  to  south  will  extend  to  the  foot  of  the  mountains.  There  need 
be  no  well-defined  wind  movement  (Fohn)  in  this  case,  at  least  not 
in  the  lower  regions.  The  so-called  Fohn-effects  (otherwise  dam- 
ming up  at  the  mountains  and  favoring  precipitation)  make  them- 
selves felt  even  with  a  comparatively  small  barometric  gradient,  and 
may  delay  for  two  or  three  days,  or  even  entirely  prevent,  the  forma- 
tion of  clouds  and  precipitation,  while  at  no  great  distance  from  our 
frontier  the  weather  undergoes  a  radical  change. 

The  study  of  the  influence  exercised  by  the  Alpine  mountain  chain 
as  a  climatic  factor  (which  may,  perhaps,  be  also  felt  in  dynamic 
meteorology)  is  of  the  utmost  importance  for  the  improvement  of  the 
forecasts  in  our  country,  and  this  study  requires  the  most  careful 
fostering  of  the  meteorology  of  the  upper  regions  through  the  estab- 
lishment of  good  observations  at  mountain  stations. — R.  Billwiller, 
Director. 

XL — The  United  States  Weather  Bureau. 

The  forecasts  and  warnings  of  the  United  States  Weather  Bureau 
are  based  upon  a  study  of  reports  of  observations  taken  daily  at  8 
a.  m.  and  8  p.  m.,  seventy-fifth  meridian  time,  at  one  hundred  and 
twenty-four  regular  reporting  stations  in  the  United  States  and  nine- 
teen points  in  Canada.  These  reports  are  promptly  telegraphed  in 
cipher  to  the  Central  Office  at  Washington  and  to  the  more  important 
Weather  Bureau  stations,  and  also  transmitted  by  telegraph  to  the 
Canadian  Central  Office  at  Toronto.  During  the  West  India  cyclone 
season  ])rovision  is  made  for  timely  reports  by  telegraph  of  disturb- 
ances noted  in  that  region. 

Instructions  covering  tlie  making  of  observations  and  filing  of  re- 
ports at  the  telegrapli  offices  allow  of  no  deviation  from  prescribed 
methods  nor  departure  from  fixed  rules.  A  reference  to  these  methods 
and  rules,  and  a  brief  statement  of  the  processes  involved  from  the 


THE    WEATHER    SERVICE.  63 

making  of  the  observations  at  the  several  stations  to  the  issue  of  the 
forecasts  and  warnings  at  the  Central  Office,  will  probably  best  illus- 
trate the  system  of  the  Bureau. 

Promptly  to  the  hour  and  minute  the  work  of  observation  is  begun 
at  each  station,  and  simultaneously  the  small  army  of  observers  per- 
forms the  several  operations  pertaining  thereto.  Within  a  specified 
period  the  enciphered  reports  are  filed  at  the  telegraph  offices  and 
placed  upon  circuits  devoted  exclusively  to  their  transmission.  At 
8.45  a.  m.  and  8.45  p.  m.,  daily,  the  work  of  deciphering  the  reports 
and  charting  the  data  is  begun  by  a  force  of  trained  experts  at 
Washington.  The  average  time  required  for  this  work  is  about  one 
hour.  Upon  the  completion  of  the  charts  the  Forecast  Official  dictates 
a  statement  of  the  general  and  special  meteorological  features  pre- 
sented by  the  reports,  prepares  the  forecasts  for  the  various  districts, 
and  issues  such  signal  orders  as  the  conditions  may  require.  The 
dictation  covering  the  synopses,  forecasts,  and  warnings  is  set  in  type 
and  also  telegraphed  as  it  progresses,  and  at  the  expiration  of  the 
thirty  to  forty-five  minutes  required  for  the  performance  of  this  work 
the  utterances  of  the  Forecast  Official  have  been  filed  for  transmis- 
sion to  all  points  in  the  United  States  reached  by  electric  telegraph. 

The  press  associations  furnish  the  daily  press  with  the  regular 
forecasts  and  warnings,  and  also  transmit  special  statements  or  bul- 
letins issued  in  anticipation  of  unusual  or  alarming  meteorological 
conditions.  In  addition  to  dispatches  transmitted  by  the  news  asso- 
ciations, weather  and  temperature,  cold  wave,  and  frost  messages  are 
telegraphed  at  Government  expense  to  specially  apj)ointed  display- 
men  and  selected  points,  exclusive  of  regular  observers  and  stations 
of  the  Weather  Bureau,  as  follows : 

Displaymen  of  weather  and  temperature  signals 1,  613 

Displaymen  of  cold-wave  signals 174 

Displaymen  of  frost  signals 458 

Total  paid  messages 2,  245 

In  addition  to  the  above,  messages  for  public  display  are  tele- 
graphed to  2,129  railroad  stations;  messages  are  telegraj)hed  or  tele- 
phoned to  620  places ;  forecasts  are  sent  by  mail  to  3,065  points ;  and 
are  delivered  by  cooperating  railroad  train  services  to  1,264  stations. 
The  total  number  of  places  to  which  the  forecasts  or  warnings  are 
sent  is  9,323.  As  before  stated,  this  number  represents  only  regularly 
authorized  display  stations,  and  does  not  include  thousands  of  per- 
sons and  places  furnished  by  the  various  local  Weather  Bureau  offices 
throughout  the  country.  In  addition  to  the  above,  and  exclusive  of 
regular  stations  of  the  Weather  Bureau,  signals  giving  warning  of 
dangerous  gales  are  displayed  at  121  points  on  the  sea  coasts  and  the 
Great  Lakes. 


64  CHICAGO    METEOROLOGICAL    CONGRESS. 

While  the  comparative  degree  of  accuracy  of  the  forecasts  for  dp- 
fined  periods  is  shown  by  the  percentage  of  verification,  the  best 
proof  of  their  value  to  the  public  is  the  increasing  demand  for  the 
predictions.  Their  distribution  is  now  limited  by,  and  coextensive 
with,  the  scope  of  the  electric  telegraph  and  telephone. 

The  regular  forecasts  of  the  Weather  Bureau  are  issued  from  the 
Central  Office  at  Washington  by  or  before  11  a.  m.  and  11  p.  m., 
seventy-fifth  meridian  time,  daily.  The  morning  forecast  is  made 
for  a  period  of  thirty-six  hours,  and  the  night  forecast  for  a  period 
of  twenty-four  hours.  In  the  discretion  of  the  Forecast  Official  fore- 
casts are  made  for  periods  of  forty-eight  hours.  The  regular,  and 
what  are  termed  twenty-four  and  thirty-six  hour  forecasts,  specify 
the  character  of  the  weather,  such  as  general  or  local  and  heavy  or 
light  rain  or  snow,  fair  or  clear  weather,  higher  or  lower  tempera- 
ture, including  terms  indicating  the  amount  of  the  anticipated  rise 
or  fall  in  temperature,  and  the  force,  direction,  and  shifts  of  the 
wind  for  each  State  or  part  of  State  east  of  the  Rocky  Mountains. 
The  remaining  States  and  Territories,  with  the  exception  of  New 
Mexico  and  Wyoming,  are  covered  by  forecasts  issued  at  San  Fran- 
cisco, Cal.,  and  Portland,  Oreg.  The  morning  forecasts  are  of 
special  value  to  outlying  or  country  districts,  as  the  messages  giving 
forecasts  for  the  following  day  can  be  sent  to  displaymen  and  points 
referred  to,  and  the  signals  and  bulletins  displayed  without  delay. 
These  forecasts  also  appear  in  all  of  the  evening  papers  of  the  coun- 
try. When  the  morning  reports  indicate  unusual  or  dangerous  me- 
teorological conditions,  special  telegraphic  rejjorts  are  called  for  and 
supplementary  warnings  are  telegraphed  to  threatened  districts  at 
the  discretion  of  the  Forecast  Official.  The  night,  or  twenty-four 
hour,  forecasts  are  of  value  chiefly  in  cities  and  towns  where  the  pre- 
dictions are  disseminated  through  the  medium  of  the  morning  news- 
papers. The  early  closing  of  telegraph  and  telephone  offices  in  the 
smaller  towns  and  villages  prevents  a  prompt  transmission  of  the 
night  forecasts  to  outlying  districts. 

The  verification  of  forecasts  for  thirty-six  hours  shown  by  the 
tables  is  determined  by  the  conditions  presented  by  the  morning  and 
evening  reports  of  the  day  succeeding  that  for  which  the  forecast  is 
made,  and  the  verification  of  the  night,  or  twenty-four  hour,  forecasts 
is  based  upon  the  data  which  are  shown  on  the  night  charts  of  the 
following  day.  Cold-wave  signals  are  verified  if  the  required  fall  in 
temperature  occurs  within  thirty-six  hours  after  the  signal  is  ordered, 
although  the  order  must  specify  the  period  within  which  the  fall  is 
anticipated.  A  forecast  of  rain  for  a  State  requires  for  a  full  verifi- 
cation that  seven-tenths  of  the  State  shall  be  embraced  within  the 
rain  area.  When  a  smaller  portion  of  the  State  is  covered  by  the 
rain  area  the  percentage  of  verification  is  proportional  to  the  area  of 


THE    WEATHER    SERVICE. 


65 


rain.  When  no  rain  falls  the  percentage  of  verification  is  zero.  Sim- 
ilarly the  percentage  of  verification  of  forecasts  of  temperature  is 
proportional  to  the  area  of  the  district  included  by  the  temperature 
changes.  Rainfall  is  considered  for  the  twelve-hour  periods  ending 
at  8  a.  m.  and  8  p.  m.,  and  verification  of  temperature  forecasts  is 
determined  by  the  twenty-four  hour  temperature  changes. 

The  following  tables  show  the  percentage  of  verification  of  rain  and 
temperature  forecasts  for  twenty-four  and  forty-eight  hours,  and  also 
the  percentage  of  verification  of  cold  wave  and  wind  signals  during 
the  last  two  years : 

Percentage  of  verification  of  rain  forecasts. 


Year  and 
month. 


Total 


Average . 


24  hours. 


48  hours. 


418 
353 
456 
334 
440 
669 
512 
480 
332 
198 
238 
414 


4,844 


65-9 
74-9 
74-3 
58-9 
72.4 
69-3 
74-9 
73-8 
70.4 
71.9 
83-4 
67.2 


71.2 


202 

53-9 

92 

65-5 

14 

47.1 

7 

78.6 

44 

21.4 

25 

63.2 

10 

70.0 

10 

74.0 

40 

36.2 

Year  and 
month. 


1893. 

January 

February  . , 

March , 

April 

May , 

June 

July 

August 

September  , 

October 

November  , 
December., 


Total  . . . 
Average . 


34  hours. 


48  hours. 


346 
649 
704 
557 
234 
493 
554 
.638 
339 
364 
472 


5.350 


67.2 
82.1 
80.2 
76.0 
77.6 

74-7 
72.4 
56.8 
73-6 
77.6 
71. 1 


73-5 


68.1 
83-9 
70.0 


62.6 


Percentage  of  verification  of  temperature  forecasts. 


1891. 

1892. 

1S93. 

24  hours. 

48  hours. 

24  hours. 

48  hours. 

24  hours. 

48  hours. 

Month. 

1 
E 

3 

6 

f 

0 

u 

u 

Or 

c 

s 

5 

4J 

c 

1 

e 
z 

s 

a 
§ 

0 
.0 

S 

a 
Z 

0 
a 

S 

3 

<B 

f 
0 

a- 

C 

XI 

s 

3 

0 

c 
2 

Oh 

Jan 

Feb 

Mar 

Apr 

May 

1,302 
1,176 
1,302 
1,260 
1,302 
r,  260 
1,302 
1,302 
1,260 
1,302 
1,260 
1.302 

83.0 

84.2 

73-0 

74-9 
80. 3 
72.1 
77-7 
7S.7 
84-3 
83-4 
81.7 
87-3 

43 
75 
23 
"5 
37 
57 
28 
392 
135 
63 
499 
199 

90.2 

88.3 

100.  0 

87.0 
97.0 

83.5 

85.0 
79.6 

75-1 
78.3 
71-7 
76.3 

1,302 
1,218 
1,302 
1,260 
1,302 
1,260 
1,302 
1,302 
1,260 
1.302 
1,260 
1,302 

85.0 

81.  I 

86. 9 
75-3 
72.0 
80.5 
82.2 
78.8 
86.1 
87-5 
84.4 
82.7 

22 
625 
120 

25 
6 
342 
15 
42 
78 
62 
31 

81.8 
71.6 
73-4 
87.2 
30.0 
72.0 
93-3 
58-8 
81.0 
77-7 
96.8 

1,302 
I,  176 
1,302 
I,  260 
1.302 
1,260 
1.302 
1,302 
1,260 
1.302 
1,260 

80.9 
85-5 
84.1 
82.5 
82.6 
81.0 
79-3 
68.4 
85-0 
81.2 
87.9 

31 
41 

48 

88.1 
72.7 
94.0 

June 

July 

Aug 

Sept 

Oct 

19 

33-2 

Nov 

Dec 



Total  ... 
Average. 

15.330 

960.6 
80.0 

1,666 

1,012.0 

84-3 

15.372 

81.9 

1.368 

73-4 

14,  028 

81.6 

139 

78.1 

66 


CHICAGO    METEOROLOGICAL    CONGRESS. 

Percentage  of  verification  of  wind  signals. 


Month. 


January  ... 
February  . . 

March 

April 

May 

June 

July 

August .... 
September . 
October..., 
November. 
December  . 


Total. 


Average  , 


1891. 


Number.  Percentage. 


87 
116 
114 

91 
76 
20 
65 
14 
50 
165 
187 
96 


1,081 


81.7 
69.7 
82.1 
67.0 
73-0 
41-5 
58-9 
41.0 
62.6 
69.9 
71.4 
76.9 


71. 1 


1892. 


Number.  Percentage. 


225 

162 

174 

239 

232 

58 

43 

42 

126 

162 

343 
170 


1,976 


69.6 
87.1 
84.1 
76.4 
67.4 
56-1 
68.7 
62. 1 
73-2 
82.2 
75.5 


77.6 


1893- 


Number.   Percentage. 


217 
191 
180 
338 
225 
128 
36 
94 
143 
336 
300 


2,188 


72-3 
83-2 

76-3 
83-7 
83-9 
70.4 

63-9 
82.0 
68.0 

74-5 
71-5 


75.6 


Percentage  of  verification  of  cold-wave  signals. 


Month. 


January  ... 
February   . 

March 

April 

October  ... 
November 
December  . 


Total . . . 
Average 


1891. 


Number.  Percentage. 


i88 
378 
114 


179 
230 


54-8 
70. 1 
54-4 


40.0 
68.8 
70.2 


1, 109 


65.2 


Number. 

Percentage. 

386 

311 
120 
61 

67.0 
62.5 

85-5 
52-7 

215 
185 

63-4 
48.1 

1,278 

63.6 

1893. 


Number.  Percentage. 


639 
295 
224 
150 
38 
229 


1.575 


56-2 
73-5 
84.0 
55-0 
60.5 
65-3 


64.7 


While  a  thorough  knowledge  of  general  meteorology,  and  of  the 
conditions  peculiar  to  the  various  districts  or  localities  for  which  the 
forecasts  are  made  is  a  recognized  qualification,  the  forecaster  must 
possess  the  ripe  judgment  gained  by  experience,  and  the  confidence 
and  aptitude  which  nature  alone  bestows,  in  order  to  become  emi- 
nently successful  in  the  practice  of  weather  forecasting.  The  prin- 
ciples upon  which  the  forecasts  depend  are  embodied  in  the  applica- 
tion of  these  necessary  qualifications  to  a  solution  of  the  problems 
presented  by  the  weather  maps.  The  tabulated  data  show  the  de- 
gree of  success  attained  in  predicting  the  several  changes  or  character 
of  weather  covered  by  the  forecasts.  Rain  or  snow  forecasts  are  ad- 
mittedly the  most  uncertain  and  are  the  forecasts  which  yield  the 
lowest  percentages  of  verification  ;  yet  this  class  of  predictions  is  un- 
doubtedly of  the  greatest  importance.  If,  therefore,  rain  can  be 
accurately  predicted  seven  times  out  of  ten  it  may  be  safely  asserted 
that  we  are  able  to  predict  rain.  As  regards  fair  weather  forecasts 
the  percentage  of  verification  is  15  to  20  per  cent  higher ;  we  may, 
therefore,  also  claim  success  in  forecasting  fine  weather.  It  is  safe  to 
say,  in  this  connection,  that  the  failures  in  rain  forecasts  are  largely 


THE    WEATHER    SERVICE.  67 

confined  to  what  are  termed  "  local  rains,"  and  that  general  and  heavy- 
precipitation  is  in  a  much  larger  percentage  of  instances  anticipated. 
The  same  may  be  said  of  the  forecasts  of  temperature ;  in  this  class 
of  forecasts  marked  and  general  changes  are  rarely  unpredicted.  The 
success  attained  in  wind  signals  is  scarcely  represented  by  the  per- 
centage of  verification,  as  in  many  instances  dangerous  winds  which 
out-going  vessels  would  encounter  will  prevail  within  a  few  hours' 
sail  of  the  port  at  which  the  signal  is  displayed  without  a  justifying 
velocity  at  the  station.  The  success  in  verifying  wind  signals,  as 
shown  by  the  table  (about  77  per  cent),  proves,  however,  that  we  are 
able  to  predict  wind  storms  for  specified  points  with  a  marked  degree 
of  success. 

In  fair  weather  the  public  desires  to  know  when  rain  or  snow  may 
be  expected,  and  when  rain  or  snow  is  falling  the  demand  is  confined 
to  enlightenment  as  to  the  duration  of  the  storm.  The  public  wishes 
to  know  when  to  prepare  for  cold  waves  and  frost,  and  requires  fore- 
casts, not  a  statement  of  existing  conditions.  The  interests  reached 
and  benefited  by  good  forecasts  are  not  confined  to  any  business, 
profession,  or  class.  Commerce  and  agriculture,  dealers  and  handlers 
of  all  description  of  goods  and  produce  subject  to  injury  by  the  ele- 
ments, the  well  and  ill,  all  have  material  or  personal  interests  which 
render  valuable  a  knowledge  of  the  weather  of  to-morrow.  At  the 
present  stage  of  the  science  of  meteorology  the  character  of  the 
weather  of  to-morrow  can  be  regularly  and  successfully  anticipated 
from  the  morning  reports  more  than  eight  out  of  ten  times.  In  cases 
where  the  changes  are  marked  the  degree  of  success  is  unquestion- 
ably greater. 

As  the  forecasts  for  forty-eight  hours  are  optional  with  the  Fore- 
cast Official,  the  percentages  given  do  not  represent  results  compara- 
ble with  the  predictions  made  for  shorter  periods ;  neither  do  they 
show  the  degree  of  accuracy  that  is  possible  in  forecasts  made  regu- 
larly for  the  longer  periods. 

The  energies  and  resources  of  the  Weather  Bureau  are  now  being 
devoted  to  attempts  to  determine  and  adopt  methods  calculated  to 
improve  the  forecasts.  Efforts  will  be  made  not  only  to  obtain  the 
best  forecasting  talent,  but  to  solve  by  well  directed  scientific  studies 
and  investigation  many  of  the  perplexing  problems  which  now  con- 
front the  forecaster. — Major  H.  H.  C.  Dunwoody,  U.  S.  A.,  Chief  of 
Forecast  Division. 


SECTION    II. 

RIVERS  AND  FLOODS. 


1.— FLOODS  OF  THE  MISSISSIPPI  RIVER,  WITH  REFERENCE  TO 
THE  INUNDATION   OF  THE  ALLUVIAL  VALLEY. 

William  Starling. 

The  Lower  Mississippi  derives  its  main  supply  of  water  from  three 
different  sources — the  valleys  of  the  Ohio,  the  Upper  Mississippi,  and 
the  Missouri.  These  regions  have  many  points  of  dissiniilarity.  The 
valley  of  the  Ohio  belongs  to  an  early  geological  period,  the  upheaval 
of  the  Appalachian  chain  having  occurred  at  the  close  of  the  Paleo- 
zoic time.  The  valley  of  the  Upper  Mississippi  was  partly  contem- 
poraneous with  that  of  the  Ohio,  while  a  part  is  of  later  date.  The 
valley  of  the  Missouri  is  of  comparatively  recent  origin.  The  Rocky 
Mountains  were  hardly  in  existence  when  the  Ohio  was  already  a 
full-grown  and  even  an  old  river.  The  place  of  the  Missouri  of  to-day 
was  then  occupied,  first  by  a  prolongation  of  the  Gulf  of  Mexico, 
afterward  by  a  series  of  great  fresh-water  lakes.  Finally,  on  the 
completion  of  the  elevation  of  the  Rocky  Mountains,  in  the  late  Ter- 
tiary period,  the  Missouri  assumed  something  like  its  present  shape, 
subject,  of  course,  to  the  subsequent  changes  of  the  Glacial,  Cham- 
plain,  and  Terrace  epochs,  by  which  its  full  development  as  a  river 
was  completed,  in  common  with  that  of  the  other  tributaries  and  of 
the  great  alluvial  valley  of  the  united  stream. 

The  physical  and  climatic  features  of  these  valleys  are  as  various 
as  their  origin.  The  Missouri  Basin  is  much  the  largest  of  the  three, 
containing  about  541,000  square  miles.  The  Ohio  Valley  is  not  half 
so  great,  possessing  a  watershed  of  only  202,000  square  miles.  Small- 
est of  all  is  the  valley  of  the  Upper  Mississippi,  with  an  area  of  only 
171,500  square  miles.  These  grand  basins  are  visited  by  rainfalls 
which  are  of  great  diversity.  In  the  Missouri  Basin  the  annual  down- 
fall is  given  by  Humphreys  and  Abbott  as  only  20.9  inches,  and  of 
this  it  is  estimated  by  the  same  authorities  that  only  15  per  cent  is 
actually  turned  into  drainage.  The  Upper  Mississippi  region  has  a 
rainfall  of  35.2  inches,  of  which  24  per  cent  makes  its  appearance  in 
the  channel  of  its  river.  In  the  Ohio  Valley  the  quantity  of  rain 
68 


p 


FLOODS    OF    THE    MISSISSIPPI.  69 


which  annually  descends  is  41.5  inches,  and  of  this,  too,  24  per  cent  is 
turned  into  the  river.  Later  observations  have  somewhat  modified 
these  figures,  but  they  will  answer  our  purpose.  Hence,  the  great 
Missouri  Basin,  with  its  enormous  area,  but  with  a  scanty  rainfall 
and  an  absorptive  soil,  and  with  drying  winds,  contributes  less  to  the 
main  river  than  the  Ohio,  with  its  rainy  and  wooded  western  moun- 
tain slopes  and  its  sharp  declivities;  and  the  Upper  Mississippi  less 
than  either.     The  respective  proportions  are  as  50,  38,  and  33. 

The  course  of  the  Ohio  is  far  more  southerly  than  that  of  either  of 
its  sister  streams.  Its  extreme  northern  tributaries  reach  hardly 
higher  than  latitude  42°,  while  to  the  southward  it  ranges  as  low  as 
latitude  34°.  Its  highest  sources  are  in  the  low  range  of  the  Appa- 
lachians, and  it  rarely  encounters  a  cold  climate.  Its  snows  thaw 
soon  and  its  mountains  catch  the  warm  winds  from  the  Gulf  of 
Mexico.  Its  greatest  rainfall  is  in  January,  February,  and  March 
therefore  its  floods  are  early,  coming  sometimes  in  January,  generally 
in  February,  though  sometimes  later.  There  is  a  record  of  a  consid- 
erable flood  in  August,  1875.  Its  greatest  tributaries  are  on  the 
left,  eastern  or  southern  side,  heading  in  the  Alleghanies,  the  streams 
on  the  opposite  side  being  short  and  comparatively  important.  The 
two  capital  tributaries,  the  Tennessee  and  the  Cumberland,  have  an 
extreme  southerly  range  and  a  great  rainfall,  and  pour  down  an  im- 
mense volume  of  flood  water.  They  never  reach  any  considerable 
height  after  April. 

The  Upper  Mississippi  runs  almost  south,  and  its  extreme  north- 
ern sources  are  frequently  locked  in  ice  until  late  in  the  spring.  Its 
southerly  tributaries  often  suffer  considerable  freshets  at  a  much 
earlier  date,  but  they  are  of  limited  extent,  and  it  is  but  seldom  that 
a  flood  of  any  consequence  appears  earlier  than  April.  Its  greatest 
rainfall  is  in  May  and  June. 

Most  of  the  feeders  of  the  Missouri  have  their  origin  on  the  eastern 
slope  of  the  Rocky  Mountains.  The  principal  rise  is  caused  by  a 
combination  of  melting  snows  and  late  spring  rains,  and  usually 
reaches  Saint  Louis  in  May  or  June.  There  are  frequently  partial 
freshets  from  early  rains  in  the  lower  part  of  the  valley  in  February 
or  March,  but  they  never  attain  the  dimensions  of  the  "June  rise,"  as 
it  is  called.  Very  little  water  falls  in  the  greater  part  of  this  im- 
mense valley  in  the  winter  months — a  good  deal  in  April,  but  the 
most  in  May  and  June. 

It  must  not  be  forgotten  that  the  Lower  Mississippi,  below  the  con- 
fluence of  the  three  great  component  streams,  receives  the  waters  of 
several  large  rivers,  some  of  them  heading  in  regions  of  heavy  rain- 
fall, with  a  very  great  percentage  of  drainage,  and  consequently  con- 
tributing, at  times,  enormous  volumes  of  water.  Two  of  these,  the 
Arkansas  and  White  rivers,  discharge  into  the  Mississippi  through  a 


70  CHICAGO    METEOROLOGICAL    CONGRESS. 

common  basin.  They  have,  jointly,  a  watershed  greater  than  that 
of  the  Upper  Mississippi,,  and  annually  pour  into  the  great  trunk 
stream  more  than  half  as  much  as  the  Missouri.  The  Saint  Franci- 
and  Yazoo  each  contribute  about  one-fourth  as  much.  Red  River, 
while  a  very  important  stream,  yet  enters  the  Mississippi  so  near  its 
mouth  that  its  floods  are  of  only  local  importance.  Moreover,  a  con- 
siderable part  of  them  passes  out  through  the  Atchafalaya. 

The  Ohio,  Upper  Mississippi,  Saint  Francis,  and  White  rivers  are 
non-sedimentary  streams.  They  flow  mostly  through  hard  forma- 
tions and  stable  beds,  and  at  low  and  medium  stages  their  waters  are 
clear.  The  Missouri,  Arkansas,  Yazoo,  and  Red  rivers  are  always 
more  or  less  muddy,  flowing,  as  they  do,  in  the  lower  portion  of  their 
course,  through  beds  of  their  own  deposits.  The  qualities  of  the  sed- 
iments which  they  bring  to  the  great  river  are  different.  That  of  the 
Missouri  is  mostly  light  and  loamy,  and  thus  is  capable  of  being 
transported  for  very  long  distances,  as  will  appear  from  the  fact  that 
the  quantity  of  matter  carried  in  suspension  at  New  Orleans  is  much 
greater  during  floods  from  the  Missouri  than  at  other  times.  The 
sediment  from  the  Arkansas  is  usually  of  a  reddish  color,  as  is  well 
known  to  the  pilots  and  other  river  men,  all  of  whom  can  tell,  by  a 
glance  at  the  waters,  whether  the  Arkansas  is. in  freshet. 

From  causes  which  will  appear  hereafter,  the  western  rivers,  the 
Upper  Mississippi,  the  Missouri,  the  Saint  Francis,  White  and  Arkan- 
sas usually  act  together.  The  Ohio  and  its  tributaries  are  governed 
by  different  conditions.  It  has  never  occurred  that  all  these  streams 
were  in  extreme  flood  at  the  same  time.  Such  an  ominous  conjunc- 
tion would  produce  a  discharge  of  more  than  3,000,000  cubic  feet, 
which  would  be  greater  by  one-half  than  has  ever  been  known.  But 
it  has  often  happened  that  an  extreme  flood  from  the  Ohio  has  met  a 
moderate  freshet  from  the  western  streams,  or  that  a  high  May  or 
June  rise  from  the  latter  has  found  the  Ohio  at  more  than  a  medium 
stage.  In  either  of  these  cases,  great  floods  may  and  do  occur  in  the 
lower  river.  In  fact,  it  is  quite  possible  for  a  very  great  flood  in 
either  the  eastern  or  western  system,  combined  with  a  merely  average 
stage  in  the  other,  to  produce  a  very  high  water  below  the  mouth  of 
the  Arkansas.  The  usual  order  of  floods  from  the  several  tributaries 
is  as  follows :  the  Ohio,  Cumberland,  and  Tennessee,  all  together ; 
then  the  Upper  Mississippi ;  then  the  Missouri,  with  probably  the 
other  western  rivers. 

It  is  often  affirmed  that  the  principal  cause  of  floods  is  the  melting 
of  the  winter's  ice  and  snow.  In  the  case  of  the  Ohio  this  statement, 
as  a  generality,  must  be  denied,  and  it  is  believed  that  this  denial 
may  be  extended  to  the  other  rivers.  Certainly,  it  may  to  the 
southern  streams,  including  the  Arkansas.  In  point  of  fact,  some  of 
the  greatest  snowfalls  ever   recorded   in  the  Ohio  Valley  have  dis- 


FLOODS    OF    THE    MISSISSIPPI.  71 

appeared  without  producing  any  considerable  effect,  and  some  of  the 
greatest  floods  have  occurred  when  there  was  no  snow  on  the  ground. 
The  most  potent  agent  in  producing  floods  has  been  excessive  rain- 
fall. This  assertion  does  not  exclude  the  action  of  snow  where  it 
exists.  On  the  contrary,  it  cooperates  with  it  most  powerfully.  A 
deep  snow,  passing  off  with  a  warm  and  heavy  rain,  of  course  greatly 
augments  the  effect  of  the  latter,  and  that  too  at  a  very  critical  time. 
Every  fraction  of  an  inch  added  to  a  considerable  rainfall  increases 
its  effective  volume  for  drainage  more  than  proportionately;  for 
instance,  in  a  dry  season,  an  inch  of  rain  will  not  much  more  than 
be  absorbed  by  the  ground,  but  if  two  inches  fall  the  additional  inch 
will  nearly  all  turn  to  drainage,  and  of  three  inches  two  will  be  avail- 
able for  river  water.  Thus,  a  three-inch  rain  wdll  be  doubly  as  dam- 
aging as  one  of  two  inches,  and  infinitely  worse  than  one  of  a  single 
inch. 

The  heaviest,  most  sudden,  most  violent,  most  extensive,  and  most 
dangerous  rains  that  occur  in  the  Ohio  Valley  are  those  accompanying 
the  cyclonic  storms  which  originate  or  have  their  fullest  development 
in  the  vicinity  of  the  Gulf  of  Mexico.  These,  as  is  well  known,  gen- 
erally first  assume  formidable  proportions  within  the  territory  of  the 
United  States  in  southeastern  Texas,  and  then  follow  the  Ohio  Val- 
ley to  the  Great  Lakes,  making  their  exit  at  the  mouth  of  the  Saint 
Lawrence  River.  They  are  usually  accompanied  by  very  low  barom- 
eter, southerly  winds,  much  thunder  and  lightning,  and  deluges  of 
rain,  which  last  is  not  merely  caught  by  the  mountain  ranges  that 
intercept  and,  as  it  w^ere,  strip  the  clouds,  but  also  falls  with  equal 
impartiality  on  all  parts  of  the  lowlands.  A  considerable  flood  has 
been  known  to  result  from  two  of  these  storms,  each  distributing 
about  three  inches  of  rain  over  the  Ohio  Valley,  at  an  interval  of 
about  a  week  apart.  The  season  was  March  to  April.  There  was  little 
snow,  and  the  rivers  were  decidedly  low.  These  storms  are  supposed,  I 
believe  (though  here  I  think  I  am  speaking  Latin  before  clerks),  to  fol- 
low- the  direction  of  the  prevailing  current  of  the  upper  air,  and  con- 
sequently generally  travel  somewhat  from  southwest  to  northeast, 
skirting  the  western  slope  of  the  Alleghanies.  Their  path  does  not 
usually  include  the  upper  waters  of  the  rivers  of  the  western  system, 
though  it  may  encounter  their  lower  portions.  They  have  been 
known  to  prevail  for  weeks,  one  following  the  other  at  intervals,  two 
or  three  in  a  month,  literally  drenching  the  whole  country  through 
which  they  passed,  as  probably  in  the  famous  season  of  1867,  and 
certainly  in  the  more  famous  one  of  1882,  In  the  latter  year,  the 
rainfall  in  the  Ohio  Valley  for  January  was  60  per  cent  more  than 
the  normal  for  the  month.  In  the  Cumberland  and  Tennessee  val- 
leys it  was  three  times  the  average.  In  the  Lower  Mississippi  Valley  it 
was  more  than  double  the  mean.     In  February,  for  the  Ohio  Valley 


72  CHICAGO    METEOROLOGICAL    CONGRESS. 

the  excess  was  70  per  cent;  for  Tennessee,  65  per  cent;  for  the  Upper 
Mississippi,  50  per  cent.  The  extreme  height  of  the  flood  was  reached 
at  Cairo  on  the  26th  of  February.  In  February,  1884  (flood  month), 
Ohio  Valley,  70  per  cent  excess ;  Tennessee,  70  per  cent.  There  was 
also  much  snow  on  the  ground.  In  January,  1890,  Ohio  Valley  and 
Tennessee,  35  per  cent  excess ;  in  February,  60  per  cent ;  in  March,  40 
per  cent.  There  was  excessive  rain  in  the  valleys  of  the  Arkansas 
and  White  rivers,  especially  the  latter,  keeping  it  near  extreme  flood 
nearly  four  months.  The  flood  in  the  lower  river  was  in  March  and 
April.  In  1892  the  Ohio  was  at  a  moderate  stage  throughout.  The 
flood  came  from  the  western  rivers,  and  culminated  at  Cairo  on  the 
27th  of  April.  Before  this  had  time  to  recede  it  was  caught  by 
another  which  reached  its  maximum  on  the  25-26th  of  May.  The 
rainfall  for  April  in  the  Upper  Mississippi  Valley  was  80  per  cent  in 
excess  of  the  mean ;  for  the  Missouri  Valley,  80  per  cent.  In  May, 
Upper  Mississippi,  80  per  cent  excess ;  Missouri,  60  per  cent ;  in  the 
valleys  of  the  Arkansas,  White,  and  Saint  Francis,  87  per  cent.  There 
was  a  great  flood  at  Saint  Louis,  the  highest  since  1858,  and  a  very 
great  one  at  Fort  Smith,  the  highest  on  record,  and  at  Little  Rock, 
the  greatest,  I  believe,  except  1833. 

Thus,  there  are  two  classes  of  floods  which  afflict  the  alluvial  plain 
of  the  Mississippi — the  early  floods  which  proceed  mostly  from  the 
eastern  rivers,  and  the  late,  which  owe  their  origin  principally  to  the 
western  streams.  The  former  usually  reach  their  height  in  the  lower 
valley  in  March,  the  latter  in  June.  Sometimes  there  occur  very 
high  waters  of  a  third  class,  intermediate  between  the  two,  in  which 
a  late  rise  from  the  Ohio  meets  an  early  freshet  from  the  Upper  Mis- 
sissippi and  Missouri,  accompanied,  as  usual,  with  sharp  rises  from 
the  low^er  streams.  Such  floods  culminate  in  April  or  May.  It  is  a 
question  which  of  these  is  most  dreaded  by  the  dwellers  in  the  allu- 
vial region.  The  March  floods  are  frequently  very  great  in  volume, 
come  up  very  rapidly,  and  take  place  at  a  very  inconvenient  and  in- 
clement season.  They  are  usually  accompanied  by  very  high,  cold 
and  persistent  winds,  often  with  chilling  rain  or  sleet  and  plenty  of 
mud  and  general  discomfort.  Now,  if  there  is  anything  which  levee 
engineers  dread,  it  is  storms  when  the  water  stands  at  a  very  high 
stage  against  their  levees.  The  river  at  such  times  is  two  miles,  or 
more,  wide.  There  are  long  stretches  over  which  the  wind  has  full 
sweep  for  eight  or  ten  miles  up  or  down  stream,  or  in  "  old  river 
lakes,"  and  a  February  or  March  "  norther  "  sometimes  gets  up  a  for- 
midable sea,  breaking  with  great  force  clean  over  the  levee  and  men- 
acing it  with  speedy  destruction.  Provision  is  made  against  this 
danger,  to  some  extent,  by  sodding  the  slopes  of  the  levees,  by  giving 
them  a  long  and  gentle  incline  towards  the  water,  and  in  the  most 
exposed  places  by  revetments  or  breakwaters  of  plank.     It  would  be 


FLOODS   OF    THE   MISSISSIPPI.  73 

easy  enough  to  make  an  effectual  defense,  as  is  done  in  Holland,  Ger- 
many and  Italy,  by  facing  the  front  of  the  dikes  with  stone,  but  that 
is  expensive,  and  the  Mississippi  levees  have  not  yet  reached  the  stage 
of  development  when  such  a  course  is  practicable.  They  are  still 
struggling  toward  completion.  Severe  and  prolonged  storms,  how- 
ever, will  cut  through  even  a  long  and  well-sodded  slope,  and  plank 
are  not  always  to  be  had  in  an  emergency.  Moreover,  the  levees  are 
in  a  state  of  transition,  and  frequently  the  sod  has  not  had  time  to 
grow,  and  it  would  not  be  proper  to  erect  permanent  and  costly  de- 
fenses when  fresh  accessions  of  earth  have  to  be  made  every  two  or 
three  years.  So  resort  must  be  had  to  temporary  expedients  for  pro- 
tection against  the  violence  of  waves,  and  chief  of  these  are  what  are 
sometimes  improperly  called  sand  bags.  Improperly,  because  the  less 
sand  there  is  in  them  the  better.  They  are  strong  and  new  sacks 
filled,  by  preference,  with  the  heaviest  and  stiffest  clay  that  can  be 
had,  though,  generally,  use  must  be  made  of  the  first  material  that 
comes  Lo  hand.  These  must  be  filled  and  placed  in  the  teeth  of  a 
howling  "blizzard,"  every  blast  of  which  cuts  through  the  men,  wet 
to  the  skin  as  they  are  with  spray  or  rain.  To  the  novice  it  always 
seems  wonderful  that  earthen  dikes  can  be  held  at  all  against  such 
heavy  odds,  and  yet  it  is  but  seldom  that  they  are  lost  from  this 
cause. 

The  engineer,  then,  would  rather  undertake  to  hold  his  levees  in 
May  or  June,  when  the  sun  is  warm,  the  air  genial  and  mild,  the 
earth  dry  and  the  days  long.  Then  his  men  are  cheerful  and  wil- 
ling, and,  if  they  are  negroes,  sing  all  the  day  as  they  work.  But  the 
planter  dreads  a  summer  flood.  Should  the  levees  break  and  he  be 
overflowed  in  March,  the  river  will  probably  subside  in  time  for  him 
to  make  a  crop.  But  if  such  a  misfortune  happen  in  May  or  June,  it 
will  be  too  late  to  calculate  on  a  full  return,  and  he  must  either  lose 
the  season  altogether  or  incur  the  expense  of  replanting  with  a  pros- 
pect of  only  half  a  crop,  or  thereabouts. 

Overflow  is  not  the  only  calamity  that  a  planter  dreads  from  a 
flood.  Even  with  the  best  constructed  levees  a  vast  quantity  of  water 
leaks  through  the  porous  natural  soil  beneath  the  base  of  the  embank- 
ment, invades  the  roots  of  his  growing  corn  and  cotton,  and  even  rises 
in  the  furrows  or  perhaps  above  the  ridges,  thus  effectually  drowning 
out  his  crops.  This  seep  water,  as  he  calls  it,  is  an  unmitigated  evil. 
Inundation  water  brings  with  it  fertilizing  silt.  Seep  water  has  been 
stripped  of  all  this  by  filtration  through  the  ground.  It  is  sterile, 
stagnant  and  foul.  It  destroys  cotton  or  corn,  and  seems  really  to 
retard  the  recovery  of  the  land  even  after  it  has  disappeared.  Ditch- 
ing will  not  always  get  rid  of  it.  This  damage,  too,  is  far  greater 
when  the  season  is  well  advanced,  for  very  similar  reasons.  Fortu- 
nately, seep  water  usually  affects  only  the  ground  immediately  adja- 


74  CHICAGO    METEOROLOGICAL   CONGRESS. 

cent  to  the  levee,  and  generally  only  the  low-lying  parts  of  that. 
Moreover,  it  does  not  injure  grass,  so  the  planter  may  turn  his  low 
grounds  into  pasture. 

The  highest  floods  that  have  ever  prevailed  in  the  Mississippi  pro- 
ceeded mainly  from  the  Ohio,  and  culminated  in  March.  These  were 
in  1882  and  in  1884,  which  are  believed  to  have  brought  down  a 
greater  quantity  of  water  at  one  time  than  any  of  which  we  have  an 
accurate  account.  The  floods  from  the  western  rivers,  while  some  of 
them  have  been  attended  by  a  discharge  not  very  much  less  than 
these,  have  usually  been  more  remarkable  for  their  duration.  '  Of 
course,  it  is  a  matter  of  the  highest  consequence  to  forecast,  if  pos- 
sible, the  progress  of  a  flood,  and  this  can  best  be  done  by  comparison 
with  the  records  of  past  experience,  to  see  if  perchance  any  analogy 
can  be  traced  which  may  lead  to  probable  inferences  for  the  future. 
With  this  view,  the  progress  of  the  different  floods  has  been  graph- 
ically indicated  by  curves  or  hydrographs  for  the  different  stations, 
and  much  study  has  been  given  to  them.  On  the  whole  they  are 
very  disappointing.  As  a  general  rule  there  is  very  little  resemblance 
between  the  various  floods  of  the  Mississippi,  even  between  those  of 
the  same  origin.  With  a  few  exceptions  there  is  hardly  any  analogy 
to  be  traced  between  the  hydrographs  of  any  two  floods  at  whatever 
interval.  The  most  remarkable  of  the  exceptions  alluded  to  is  that 
of  the  three  years,  1882,  1883,  and  1884,  which  exhibited  a  great  simi- 
larity. All  came  princii:)ally  from  the  Ohio ;  all  culminated  at  Cairo, 
from  the  22d  to  the  27th  of  February,  at  a  gauge  height  varying  from 
51.79  to  52.17,  being  the  highest  on  record;  and  neither  was  much 
complicated  with  the  western  rivers.  The  floods  of  1892  and  1893 
also  presented  a  general  similarit}^,  each  culminating  in  the  lower 
river  about  the  first  of  June. 

It  might  be  thought  that  it  would  be  an  easy  matter  to  predict 
from  a  given  rainfall  in  the  several  valleys  the  stage  to  be  reached  at 
the  different  points  along  the  course  of  the  main  river,  but  in  reality 
it  is  a  very  complicated  problem.  It  has  already  been  seen  that  the 
ratio  between  downfall  and  drainage  is  very  diverse  in  the  several 
watersheds,  and  even  in  any  one  region  this  rate  differs  from  itself 
by  a  very  wide  range  of  discrepancy,  according  to  season  and  cir- 
cumstances. A  rain  of  say  three  inches  in  January  does  not  by  any 
means  signif}'-  the  same  thing  as  a  rain  of  three  inches  in  June.  In 
the  one  case  the  ground  is  frozen,  the  skies  are  mostly  cloudy,  the 
days  are  short,  the  air  is  cold,  the  trees  are  bare  of  foliage,  the  earth 
without  any  cover  of  vegetation.  It  is  well  known  that  taking  the 
average  of  a  whole  year  there  is  no  very  great  difference  between 
rainfall  and  evaporation ;  but  the  ratio  between  these  two  elements 
for  the  several  months  is  widely  diverse.  Observations  made  during 
a  period  of  143  years,  at  a  station  in  Holland,  on  the  border  of  Haar- 


FLOODS    OF    THE    MISSISSIPPI.  75 

lem  Lake,  show  that  during  November,  December,  and  January  the 
rainfall  is  about  four  times  the  evaporation.  In  May  and  June  the 
evaporation  is  about  double  the  rainfall.  In  March  the  two  are 
about  equal.  The  course  of  the  seasons  is  different  in  this  country, 
and  in  the  Mississippi  Valley,  at  least,  would  seem  to  be  about  a 
month  later. 

Now,  in  June,  the  earth  is  'dry,  porous,  and  receptive,  the  sun  hot, 
the  air  has  greater  capacity  for  moisture,  the  days  are  at  their 
greatest  length,  and  the  whole  surface  of  the  ground,  wild  or  culti- 
vated, woodland,  field,  plantation,  or  meadow,  is  covered  with  leafage. 
It  is,  therefore,  often  found  that  a  storm  which  would  have  produced 
a  calamitous  freshet  in  winter  or  early  spring,  raises  the  rivers  but  a 
few  feet  in  summer.  Hence  it  is,  for  one  thing,  that  spring  is  the 
season  for  floods.  It  is  not  that  the  rain  is  so  much  heavier,  or  that 
the  quantity  of  snow  on  the  ground  is  so  great,  but  that  whatever 
does  fall  is  in  a  great  measure  converted  into  river  water.  Those 
engineers  who  have  investigated  the  question  of  water  supply  for 
cities  have  found  that  the  proportion  of  rainfall  which  finds  its  way 
into  the  water  courses  is,  in  January,  about  nine-tenths ;  in  June, 
four-tenths;  in  August,  one-tenth. 

There  are  many  other  considerations  which  greatly  influence  the 
height  of  floods.  One  of  them  is  the  condition  of  the  ground  as  to 
moisture  when  the  decisive  rainfall  occurs.  It  may  be  that  this  is 
already  saturated  with  previous  rains  or  by  melting  snows,  so  that  it 
will  not  readily  absorb  any  more,  and  this  independently  of  season. 
It  has  already  been  remarked  that  a  sudden  and  heavy  rain,  a  "cloud 
burst,"  as  it  were,  produces  rises  in  the  streams  out  of  proportion  to 
•the  actual  quantity  of  water  which  falls,  and  two  or  more  of  these, 
with  only  a  short  interval  between,  may  bring  about  a  disastrous 
flood  when  the  same  rainfall,  spread  over  a  month,  would  have  been 
comparatively  harmless. 

A  very  important  element  to  be  considered,  as  regards  the  stage  to 
be  attained,  especially  in  the  lower  trunk,  is  the  height  at  which  the 
principal  rise  finds  it.  It  is  a  proverb  among  the  denizens  of  the 
Mississippi  Valley  that  a  full  river  on  the  first  of  January  portends 
an  overflow  in  the  spring.  This  simply  signifies  that  it  is  an  unfa- 
vorable prognostic,  so  far  as  it  goes,  for  the  March  rise  to  find  the 
lower  river  already  occupied  by  a  great  volume  of  water.  Suppose 
a  heavy  storm  in  the  Ohio  Valley  to  produce  a  rise  of  25  feet  at 
Cincinnati,  Nashville,  and  Chattanooga.  It  is  obvious  that  it  makes 
a  great  difference  to  the  people  of  Greenville,  in  Mississippi,  whether 
this  freshet  finds  the  river  at  that  point  already  standing  at  85  feet 
or  15  feet. 

A  second  element  of  great  consequence  is  the  duration  of  the  rise. 
A  freshet  which  rapidly  goes  up  to  50  feet  at  Cairo  and  then  as  rap- 


76  CHICAGO    METEOROLOGICAL    CONGRESS. 

idly  falls,  as  in  1886,  is  less  formidable,  and  will  actually  reach  a  less 
height  at  lower  stations  than  one  which  is  a  foot  or  two  lower  at  the 
head  of  the  alluvial  basin  at  Cairo,  but  remains  at  that  stage  for  a 
week  or  more. 

A  third  controlling  element  of  a  flood  in  the  lower  river  is  the  local 
rainfall  in  the  southern  portion  of  the  basin,  which  is  sometimes  so 
great  as  to  kee^D  that  part  of  the  river,  for  weeks,  higher  by  several 
feet  than  the  normal  relation  between  the  gauges  would  prescribe. 
The  rainfall  in  the  lower  part  of  the  valley  is  sometimes  extremely 
heavy.  In  the  Yazoo  Basin  the  rainfall  for  April,  1874,  was  22  inches. 
In  1893,  the  present  year,  the  rainfall  at  Helena,  in  May,  in  a  single 
week,  was  14^  inches,  and  the  quantity  of  water  which  fell  in  the 
Saint  Francis  Basin  was  sufficient  to  maintain  the  stage  at  Helena 
above  45  feet  on  the  gauge  for  about  two  weeks,  when  its  normal 
stage  should  have  been  42,  or  less. 

The  rate  of  travel  of  the  flood  wave  is  a  subject  of  much  interest 
and  importance,  and  it  might  be  thought  that  it  would  be  very  easily 
predicted  by  a  reference  to  the  experience  of  former  years.  It  is 
liable,  however,  to  several  perturbations.  It  is  influenced  by  slope 
and  by  height  of  stage,  and  is  complicated  by  the  intervention  of 
tributaries  and  reservoirs.     A  word  as  to  the  latter. 

While  a  great  part  of  the  alluvial  plain  of  the  Mississippi,  from 
Cairo  to  the  Gulf,  is  defended  by  levees,  yet  there  are  two  large  ter- 
ritories which  are  nearly  destitute  of  such  protection.  These  are  the 
great  basin  of  the  Saint  Francis  and  the  lesser  plain  which  spreads 
out  between  the  hills  and  the  Mississippi,  at  the  confluence  of  the 
White  and  Arkansas  rivers  with  the  trunk  stream.  The  upper  part 
of  the  latter  district  will  soon  be  shut  off  by  levees,  when  its  disturb- 
ing influences  will  in  a  great  measure  cease,  except  as  complicated 
w4th  the  action  of  the  great  tributaries  which  empty  into  it.  The 
Saint  Francis  Basin  is  likely  to  maintain  its  present  condition  for 
several  years.  In  fact,  few  active  steps  have  yet  been  taken  for  its 
reclamation.  There  are  several  such  great  bottoms  in  the  Mississippi 
Valley,  defined  by  the  approach  of  the  tertiary  hills  on  either  side, 
each  having  its  characteristic  tributary  stream,  but  most  of  them 
have  been  inclosed  by  levees,  and  need  not  be  considered  with  refer- 
ence to  our  present  subject.  The  Saint  Francis  Basin,  however,  exer- 
cises a  very  important  influence  upon  the  flood  stages  of  the  river  in 
its  front  and  for  some  distance  below  it. 

This  basin,  or  bottom,  is  merely  a  large  tract,  some  6,000  square 
miles  in  area,  of  alluvial  land,  intersected,  however,  by  one  or  two 
ridges  of  an  older  period,  and  bounded  by  the  Mississippi  on  the  east, 
and  by  the  hills  called  Crowley's  Ridge  on  the  south  and  west.  •  The 
minor  features  of  this  basin  were  much  disturbed  by  the  earthquake 
of  1811,  which  exhibited  its  greatest  activity  in  the  neighborhood  of 


FLOODS    OF    THE    MISSISSIPPI.  77 

New  Madrid,  on  its  eastern  border.  Crowley's  Ridge  forms  a  con- 
tinuous chain,  abutting  upon  the  river  at  Helena,  and  is  far  above 
the  level  of  the  highest  waters  of  the  Mississippi.  The  bank  of  the 
basin  is  low  and  liable  to  overflow,  except  where  protected  by  a  few 
local  levees.  At  a  stage  of  about  42  feet  on  the  Cairo  gauge  the 
water  begins  to  pour  over  the  bank  below  New  Madrid  and  to  fill  up 
the  "  sunken  lands"  and  other  depressions  in  the  bottom.  As  the 
river  rises  the  overflow  becomes  greater  and  greater,  and  the  water 
begins  to  drain  off  through  the  water  courses  tributary  to  the  Saint 
Francis,  and  finally  to  inundate  the  ridges  and  spread  broadcast 
over  the  whole  basin.  It  then  moves  slowly  southward,  impeded 
by  its  own  shallowness,  by  forests  and  canebrakes,  and  by  three  rail- 
road embankments,  until  it  reaches  the  hills,  when  it  is  turned  east- 
ward, being  discharged  into  the  Mississippi  in  the  vicinity  of  the 
mouth  of  the  Saint  Francis  just  above  Helena.  The  bottom  then 
acts  as  a  vast  reservoir,  receiving  at  the  upper  end  and  discharging  at 
the  lower  a  volume  equal  to  about  one-fourth  of  the  entire  contents 
of  the  Mississippi.  It  is  obvious  that  the  effect  of  this  action  will  be 
to  depress  the  flood  line  in  the  main  river  opposite  the  upper  portion 
of  the  basin.  It  appears  also  to  the  great  majority  of  engineers  that 
it  raises  the  flood  line  near  to  and  below  the  mouth  of  the  Saint 
Francis.  Not  that  the  total  discharge  is  materially  greater  than  it 
would  have  been  if  there  had  been  no  basin  at  all,  but  by  the  loss  of 
energy  incurred  in  losing  and  restoring  the  vast  volume  of  water. 
When  the  latter  is  returned  it  is  poured  into  the  Mississippi  with  a 
sluggish  velocity  and  at  an  unfavorable  angle,  so  that  it  acts  as  a 
clog  upon  the  latter,  which  has  all  that  it  can  do  to  transport  its  own 
mass  against  the  resistance  of  friction.  Therefore,  an  engorgement 
must  ensue  until  the  united  waters  acquire  head  enough  to  confer  the 
requisite  velocity. 

What  is  still  more  clear  is  that  the  crest  of  the  flood  is  greatly  re- 
tarded in  its  passage  from  Cairo  to  Helena.  At  the  ordinary  rate  of 
movement  of  flood  waves,  even  at  lower  stages,  the  passage  should 
occupy,  in  a  confined  river,  only  about  five  or  six  days.  Under  exist- 
ing conditions  it  usually  takes  from  eleven  to  fifteen  days.  In  1890 
it  consumed  seventeen  days,  and  in  1891  it  took  twenty-two  days. 
This  prolongation  by  so  many  days  of  the  time  of  trial  is  as  endur- 
able to  those  subjected  to  it  as  a  like  number  of  hours  would  be  in  a 
dentist's  chair  or  on  a  surgeon's  table.  Not  only  is  the  danger  in- 
creased in  direct  proportion  to  the  time  of  exposure,  but  additional 
hazards  are  incurred  in  the  softening  of  the  earth  of  the  levees  and 
undergrounds,  the  gathering  volume  of  seep  water,  and  the  liability 
to  be  caught  by  other  floods  supervening  on  that  which  is  present. 

The  engorgement  at  Helena  produced  by  the  return-flow  from  the 
Saint  Francis  Basin  had  formerly  a  parallel,  before  the  closure  of  the 


78  CHICAGO    METEOROLOGICAL    CONGRESS. 

Yazoo  Basin,  at  the  foot  of  the  latter  at  Vicksburg,  and  another  at 
the  mouth  of  Red  River,  acting  as  the  receptacle  of  the  flood  waters 
of  the  Tensas  Basin.  The  engorgement  is  only  locaj  ;  the  increased 
height  and  slope  conferring  a  more  than  average  velocity,  which  soon 
"  flattens  out "  the  flood  wave,  so  that  100  miles  beloAv  Helena  it 
would  signify  little  whether  the  Saint  Francis  Basin  were  closed  or 
not,  were  it  not  for  the  intolerable  retardment  of  the  flood. 

In  applying  the  records  of  past  observations  to  the  purpose  of  de- 
ducing therefrom  the  probable  stages  to  be  attained  by  a  flood  just 
coming  in  sight,  it  is  indispensable  to  have  an  accurate  knowledge  of 
the  changes  that  have  occurred  and  that  are  continually  occurring  in 
the  lower  river,  especially  in  the  way  of  levee  building.  During  the 
period  from  1882  to  the  present,  and  especially  since  1884,  there  has 
been  tremendous  progress  made  in  this  direction,  by  which  the  whole 
high-water  regimen  of  the  Lower  Mississippi  has  undergone  a  radical 
alteration.  It  is  very  difiicult,  therefore,  to  derive  much  instruction, 
in  the  forecasting  of  flood  stages  and  periods,  by  a  direct  comparison 
of  the  records  of  years  anterior  to  1885,  and  below  Arkansas  City, 
anterior  to  1888.  This  is  the  more  to  be  regretted,  for  1882,  1883 
and  1884  were  undoubtedly  three  of  the  greatest  floods  that  ever 
occurred,  particularly  the  first  and  last.  The  principal  changes  that 
have  occurred  are  the  complete  closure  of  the  Yazoo  front  in  1884-'85, 
the  rebuilding  of  the  Arkansas  levees  of  the  Tensas  front  in  1886-'87, 
and  the  raising  and  strengthening  of  all  the  different  works  of  this 
class  which  has  been  constantly  going  on  ever  since.  It  is  necessary 
to  bear  these  alterations  continually  in  mind,  in  attempting  to  reason 
from  the  older  data,  else  we  shall  make  serious  mistakes.  In  attempt- 
ing, again,  to  apply  analogies  based  upon  any  great  flood  year,  we 
must  know  the  circumstances  which  prevailed  in  that  year,  especially 
whether  any  crevasses  occurred,  and  if  so,  when  and  how  large,  and 
how  extensive  was  their  influence.  For  instance,  in  1882,  in  some 
places,  half  the  water  of  the  river  went  over  the  banks.  In  1890 
there  were  many  localities  where  one-fourth  of  the  discharge  was  lost 
in  the  same  way.  In  1892  two-thirds  of  the  portentous  outpour  of 
the  Arkansas — more  than  half  that  of  the  Missouri  at  full  flood — never 
reached  the  Mississippi  at  all,  unless  it  may  have  been  through  the  Red 
River,  but  went  around  the  head  of  the  Tensas  system  of  levees.  It 
is  want  of  acquaintance  with  these  details  which  has  gone  so  far  to 
cause  the  pherK)mena  of  the  Mississippi,  in  time  of  high  water,  to  be  re- 
garded as  anomalous,  and  has  caused  the  failure  of  many  predictions. 

It  is  evident,  then,  that  if  any  instruction  is  to  be  derived  from  the 
records  of  the  past,  it  must  be  as  the  result  of  attentive  study,  and 
that  any  conclusion  drawn  from  such  records  must  be  in  the  nature 
of  a  calculation  in  which  all  the  perturbing  influences  must  be  taken 
into  account.     There  are  several  methods  which  promise  a  hope  of 


FLOODS    OF    THE    MISSISSIPPI.  79 

success  in  this  way.  If  discharge  observations  have  been  systemat- 
ically taken  at  any  point,  for  instance  Arkansas  City,  and  a  certain 
ratio  of  progression  established  between  the  discharge  and  the  height 
of  the  gauge,  then  if  the  probable  discharge  can  be  predicted  the 
flood  height  may  become  known.  Again,  if  we  can  find  any  gauge 
which  has  not  been  subjected  to  disturbing  influences,  but  has  re- 
mained unaltered  for  many  years,  and  if  we  can  trace  any  parallelism 
or  any  known  relation  whatever  between  it  and  the  gauges  below,  at 
stages  less  than  the  highest,  then  by  analogy  the  relation  may  be  ex- 
tended to  extreme  heights.  Such  a  gauge  is  that  of  Cairo.  If,  there- 
fore, the  stage  at  Cairo  be  given,  or  can  be  calculated,  the  heights  of 
the  lower  stations  may  be  estimated.  Now,  it  is  possible  from  close 
observation  of  the  rises  in  the  great  tributaries,  or  even  from  the  re- 
ports of  the  rainfall,  to  make  a  pretty  fair  approximation  to  the  stage 
to  be  reached  at  Cairo  by  any  flood,  and  the  probable  discharge  can 
be  estimated  from  the  stage  and  other  circumstances. 

Discharge  ol)servations  have  been  taken  at  several  points  with  con- 
siderable care,  and,  though  scattered  and  fragmentary,  they  extend 
over  a  period  of  many  years.  So  far  as  any  hope  is  concerned  of 
deducing  a  regular  relation  between  discharge  and  stage,  they  are 
extremely  disappointing,  for  they  are  discrepant  and  apparently  capri- 
cious beyond  measure,  and  frequently  show  that  the  greatest  volume 
passes  at  a  stage  much  below  the  maximum,  even  several  feet  below. 
Some  of  the  disturbing  causes  are  known  and  calculable.  Others  are 
still  involved  in  much  obscurity.  In  the  present  state  of  our 
knowledge,  then,  not  much  assistance  is  to  be  derived  from  this 
method. 

The  relations  between  the  several  gauges  have  been  made  the  sub- 
ject of  study  by  several  engineers,  particularly  b}''  Colonel  Suter  and 
Captain  Rossell,  of  the  Corps  of  Engineers,  United  States  Army,  who 
have  drawn  many  interesting  conclusions.  As  an  example  of  the 
application  of  this  method  it  may  be  said,  roughly  speaking,  that 
under  ordinary  circumstances  a  stage  of  say  48  feet  on  the  Cairo 
gauge  corresponds  to  about  46.5  at  Helena,  49  at  Arkansas  City,  44 
at  Greenville,  and  48.5  at  Vicksburg.  Of  course,  these  figures  are 
subject  to  modification  in  all  sorts  of  ways,  by  the  behavior  of  tribu- 
taries and  reservoirs,  by  diversities  of  slope,  by  duration  of  flood, 
and  by  other  causes,  all  of  which  must  be  taken  into  account  if  an 
estimate  is  to  be  at  all  accurate — and  even  half  a  foot  is  a  matter  of 
serious  consequence  at  the  top  of  a  great  flood.  The  local  "  river 
prophets  "  have  acquired  considerable  skill  in  this  sort  of  prediction  ; 
and  when  once  the  extreme  height  at  Cairo  has  been  reached,  or 
plausibly  calculated,  they  can  foretell  the  progress  of  the  flood  down 
stream  within  pretty  narrow  limits.  As  to  general  prognostications, 
they  also  have  a  number  of  saws,  such  as  the  one  already  quoted, 


80  CHICAGO    METEOROLOGICAL    CONGRESS. 

that  a  full  river  on  the  Ist  of  January  indicates  an  overflow  in  the 
spring.  Another  is,  that  an  "  open "  or  mild  winter  forebodes  high 
water,  and  a  severe  winter  low  water.  So  far  as  spring  floods  are 
concerned,  this  view  is  rational  enough.  Warm  winters  imply 
southerly  winds  and  Gulf  storms — cold  ones,  high  barometer  and 
winds  from  the  north  and  west.  As  to  summer  floods,  they  depend 
on  more  remote  causes. 

The  most  wearisome,  exhausting  and  dangerous  floods  are  those 
which  are  composed  of  a  succession  of  rises,  each  one  catching  its 
predecessor  before  the  latter  has  had  time  to  subside.  The  beginning 
of  a  flood  wave  travels  very  fast.  When  the  river  is  50  feet  at  Cin- 
cinnati and  25  feet  at  Cairo  the  slope  is  steep  and  the  topmost  layers 
of  water  move  at  a  great  speed.  On  the  contrary,  the  rate  of  reces- 
sion is  slow.  When  the  river  is  25  feet  at  Cincinnati  and  50  feet  at 
Cairo  the  movement  of  the  wave  is  sluggish,  and  it  is  easily  overtaken 
by  a  sharp  freshet.  In  this  it  is  aided  by  the  tributaries  near  the 
main  stream,  fed  by  the  rainfall  in  the  interior  valley,  which  pour 
forth  their  floods  almost  instantly,  and  check  the  fall  in  a  very  short 
time.  An  inspection  of  the  hydrographs  of  say  Cairo  and  Vicksburg 
shows  a  series  of  elevations  and  depressions  in  the  former  where  the 
latter  exhibits  an  almost  unbroken  rise.  The  great  number  of  the 
tributaries  of  the  Mississippi  makes  it  peculiarly  obnoxious  to  these 
incidents.  When  the  Ohio,  Cumberland,  and  Tennessee  have  begun 
falling  at  a  good  rate,  "  it  is  pretty  hard,"  as  Sir  Lucius  O'Trigger  would 
say,  if  a  freshet  can  not  come  from  the  Upper  Mississippi  or  the  Illinois 
and  keep  the  water  up  at  Cairo  till  the  eastern  rivers  have  got  their  sec- 
ond wind,  or  failing  that,  if  the  White  and  Arkansas  can  not  give  it  a 
fillip,  just  to  keep  the  ball  in  play.  I  hope  none  of  my  audience  knows 
the  feeling  of  hope  indefinitely  postponed  that  seizes  upon  the  sufferer 
who  has  been  "  fighting  high  water,"  as  it  is  very  appropriately  termed, 
for  two  months,  and  who  has  been  for  two  weeks  anxiously  waiting 
for  the  fall  at  Cairo  to  reach  him,  on  hearing  that  there  has  been  a 
rainfall  of  6  inches  at  Fort  Smith  and  Little  Rock,  and  a  rise  of  14 
feet  in  twenty-four  hours. 

The  damage  done  by  overflows  in  the  Mississippi  Valley  is  generally 
much  overrated.  The  loss  of  life  is  usually  absolutely  nothing.  Un- 
less one  is  unfortunate  enough  to  live  actually  just  behind  a  levee 
when  it  breaks,  or  to  be  standing  upon  it,  there  is  very  little  danger. 
The  reason  of  this  is  that  the  drainage  is  excellent,  and  all  toward 
the  back  country,  and  that  the  fall  of  the  water  surface  is  very  rapid, 
the  water  spreading  in  all  directions,  and  filling  up  the  swamps  very 
slowly. 


FLOOD    PLANES    OF    THE    MISSISSIPPI. 


81 


No.  2.— FLOOD  PLANES  OF  THE  MISSISSIPPI  RIVER. 

J.   A.   OCKERSON. 

A  resolution  of  Congress,  approved  in  February,  1871,  provides  that 
water  gauges  should  be  established  and  "  daily  observations  made  of 
the  rise  and  fall  of  the  Lower  Mississippi  River  and  its  ohief  tribu- 
taries "  at  nineteen  specified  points,  eleven  of  which  are  on  the  Mis- 
sissippi River  between  Saint  Louis  and  the  Gulf  of  Mexico. 

These  gauges  were  established  in  the  fall  of  1871,  and  from  that 
time  to  the  present  the  records,  with  a  few  exceptions,  have  been  con- 
tinuous and  the  information  derived  from  them  becomes  more  and 
more  valuable  with  the  lapse  of  time. 

Prior  to  1872  the  records  of  high  water  were  kept  at  several  points 
on  the  river,  extending  back  to  near  the  beginning  of  the  present 
century.  Some  of  these  earlier  records  are  accepted  as  authentic. 
The  best  of  them  are  those  of  Saint  Louis  and  Natchez.  The  chief 
difficulty  found  in  verifying  them  is  the  lack  of  well-defined,  fixed 
reference  points,  which  alone  could  prove  to  the  entire  satisfac- 
tion of  the  engineer  that  the  results  recorded  are  correct.  In  their 
absence  we  are  compelled  to  accept  the  records  kept  by  careful,  con- 
scientious observers,  with  the  feeling  that  they  are  probably  nearly 
correct. 

In  188^  several  new  gauge  stations  were  added  by  the  Mississippi 
River  Commission,  and  others  have  been  added  by  the  United  States 
Weather  Bureau,  so  we  now  have  forty-five  gauges  between  Saint  Paul, 
Minn.,  and  the  Gulf  where  daily  readings  are  made.  The  location 
of  these  gauges  is  shown  in  the  following  table : 

Water  gauges  on  the  Mississippi  River. 


Location. 


Distance 

I  from  the 

Gulf  of 

Mexico. 


Gauge  zero 
above  mean 
Gulf  level. 


Gauge  readings. 


Bank-full 


Lowest. 


Highest. 


Saint  Paul,  Minn 

Hastings,  Minn 

Winona,  Minn 

La  Crosse,  Wis 

North  McGregor,  Iowa 

Dubuque,  Iowa 

Le  Claire,  Iowa 

Roek  Island,  HI 

Muscatine,  Iowa 

Keokuk,  Iowa 

Warsaw,  111 

Quincy,  111 

Hannibal,  Mo 

Louisiana,  Mo 

Grafton,  111 

Alton,  III 

Saint  Louis,  Mo 

Chester,  111 

Cape  Girardeau,  Mo 

Grays  Point,  Mo 

Cairo,  111 

*In  1844  the  stage  reached  41 

6 


Miles. 
1,969 
1,942 
1,844 
1,812 
1.737 
1,678 
1,588 
1.571 
1.542 
1.443 
1,438 
1,401 
1,381 
1,352 
1,276 
1.263 
1,240 
1, 164 
1,107 
1, 102 
1,057 
4  feet. 


Feet. 
683. 
669. 
639- 
627. 
603. 
583- 

t554- 
541- 
529- 
475- 

t474- 
457- 
448. 
436- 
212. 
213- 
378. 

t34o. 

t30i- 
300. 
269. 


Feet. 
0.1 
—0.7 

-1-3 

0.0 

1-7 

0.9 

0.0 

—0.8 

—0.1 

—0.8 

0.0 

l.o 

-1.7 

—1.8 

190.0 

189.0 

0.0 

0.9 


Feet. 


Feet. 


0.9 


19.7 

16.9 

17.4 

15.8 

21.8 

14-5 
19.4 

17-3 

21-5 

21.4 
21.5 
21.6 
21.9 

215-8 
218.6 

w 

14 

an 

*35-9 

36-4 
35-0 
52.2 

32 

31 
4« 

t  Elevation  approximated. 


82 


CHICAGO    METEOEOLOGICAL    CONGRESS. 
Water  gauges  on  the  Mississippi  River — Continued. 


Location. 


Belmont,  Mo 

New  Madrid,  Mo 

Cottonwood  Point,  Mo. ... 

Fulton,  Tenn 

Memphis,  Tenn 

Mhoon  Landing,  Miss 

Helena,  Ark 

Sunflower,  Miss 

Mouth  White  River,  Ark. 

Arkansas  City,  Ark 

Greenville,  \iiss 

Lake  Providence,  La 

Vicksburg,  Miss 

Saint  Joseph,  La 

Natchez,  Miss 

Red  River  Landing,  La... 

Bayou  Sara,  La 

Baton  Rouge,  La 

Plaquemine,  La 

Donaldsonville,  La 

College  Point,  La 

Carrol  1  ton.  La 

New  Orleans,  La 

Fort  Jackson,  La 


Distance 
from  the 
Gulf  of 
Mexico. 


Miles. 

i>o39 
989 

937 
885 
830 
784 
754 
707 
667 
£22 
582 
518 
461 
412 
372 
307 
272 
238 
218 
186 
168 

"5 
107 

33 


Gauge  zero 
above  mean 
GulfleveL 


Feet. 

•265. 88 

254-54 

229. 36 

207.29 

182.71 

160. 22 

140.72 

125.82 

107.47 

95.18 

86.74 

68.36 

44.78 

31.48 

15-63 

2-59 

2.69 

— 1.20 

— 0.20 

—2.12 

— 0.02 

—0-35 


—1.98 


Gauge  readings. 


Lowest.       Highest 


Feet. 

14 
— 0.2 
—0.4 

1.6 
—0.9 
— 2.2 
—0.2 

2.1 

0.0 

0-3 

1.8 

-3-8 

—3-9 

—4.0 

0.0 

0.0 

—2.1 

0.9 

0.2 

1-7 

0.0 

—1.6 


0-5 


Feet. 
45-8 
41-5 
37-8 
36-7 
35-6 
40.2 
48.1 
42.9 
50-4 
50.2 

44-3 
41.9 

49-0 
45-1 
48.6 
48.9 
42.2 
38-4 
33-8 
30.6 
26.0 
17.4 
17.9 
6.9 


Bank-full 
stage. 


41 
34 
36 
35 
31 
32 
42 
36 
44 
42 
40 
36 
44 
40 
46 
42 
38 
33 
28 


The  distances  from  the  Gulf  of  Mexico,  given  in  the  above  table,  are 
channel  distances  above  Saint  Louis  and  mid-bank  distances  below 
that  point  to  the  Gulf.  The  elevations  of  gauge  zeros  are  derived 
from  duplicate  lines  of  precise  levels  extending  from  tide  water  of 
the  Gulf  along  the  river  to  Saint  Paul.  The  lowest  and  highest 
readings  given  are  the  lowest  and  highest  stages,  respectively,  that 
have  been  recorded  from  the  time  the  gauge  was  established  until 
July  1,  1893. 

Bank-full  stage  means  that  stage  of  water  which  reaches  the  top  of 
the  average  banks  in  the  vicinity  of  the  gauge. 

From  the  above  table  the  slopes  at  high  and  low  stages  between 
successive  gauges  may  be  deduced. 

Gauges  have  also  been  established  on  all  the  principal  rivers  of 
the  United  States,  and  the  river-stage  bulletin  of  1892,  issued  by  the 
Weather  Bureau,  comprises  daily  readings  at  160  stations. 

The  credit  of  developing  this  department  of  the  Weather  Bureau 
belongs  to  Prof.  Thomas  Russell,  and  the  last  bulletin  bears  strong 
evidence  of  his  energy  and  good  judgment. 

Carefully  kept  and  accurate  continuous  records  of  this  kind  will 
become  invaluable  to  the  future  engineer  who  takes  up  the  study  of 
decrease  in  flow  of  streams.  Careless  records  are  misleading  and 
worse  than  none,  and  it  is  to  be  hoped  that  the  Secretary  of  Agri- 
culture will  see  the  necessity  of  keeping  this  department  in  the 
hands  of  a  man  who  fully  appreciates  its  importance,  and  has  the 
skill  and  judgment  necessary  to  secure  and  digest  the  desired  results. 

The  flood  planes  of  the  river  become  more  and  more  marked  as  we 


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FLOOD    PLANES    OF    THE    MISSISSIPPI.  83 

approach  the  mouth  of  the  Ohio  River,  and  the  floods  grow  more  and 
more  destructive  as  the  accumulated  waters  of  the  tributaries  roll 
down  the  vast  alluvial  plain  toward  the  Gulf.  Hence  the  principal 
data  here  considered  is  that  of  the  Mississippi  River  below  the  mouth 
of  the  Missouri. 

The  table  on  p.  86  gives  the  highest  stages  reached  at  numerous 
points  during  the  period  1872  to  1893.  It  embraces  one  station 
(Hermann)  on  the  Missouri  River  and  one  (Paducah)  on  the  Ohio 
River.  The  duration  of  the  floods  above  bank-full  stage  is  also  given 
for  many  of  the  stations. 

The  locations  of  these  gauges  are  shown  on  Plate  ii.  An  inspection 
of  these  locations  shows  plainly  that  the  maximum  stage  at  Saint 
Louis  will  be  reached  by  a  concurrence  of  high  stages  in  the  Missouri 
and  Mississippi. 

The  drainage  basin  above  Saint  Louis  measures  about  699,000 
square  miles,  and  the  total  annual  discharge  averages  236,000  cubic 
feet  per  second,  the  lowest  being  about  45,000  cubic  feet  per  second, 
and  the  highest,  that  of  the  flood  of  1892,  1,146,000  cubic  feet  per 
second. 

Plate  III  gives  a  graphical  representation  of  the  highest  annual 
stages  and  the  dates  of  their  occurrence  from  J872  to  1893. 

The  maximum  stage  of  each  year  at  the  different  stations  is  shown 
by  a  heavy  vertical  line.  The  length  of  this  line  shows  the  stage 
reached,  the  horizontal  spaces  representing  two  feet  on  gauge.  The 
position  of  the  line  shows  the  date  when  the  maximum  stage  occurred. 
The  numbers  indicate  the  year. 

It  is  evident  from  an  inspection  of  this  plate  that  in  that  period 
there  has  been  no  such  coincidence  of  floods  in  the  Missouri  and  Mis- 
sissippi rivers.  As  a  rule,  the  floods  of  the  Missouri  come  consid- 
erably later  than  those  of  the  Upper  Mississippi.  The  greatest  floods 
at  Saint  Louis,  during  the  period  under  consideration,  occurred  in 
1883  and  1892.  Both  of  these  came  from  the  Missouri.  These  stages 
were  exceeded  in  1844,  1851,  and  1858.  That  of  1844  was  5  feet  higher 
than  any  other  well-authenticated  flood.  It  is  said  that  both  the 
Upper  Mississippi  and  the  Missouri  rivers  were  extraordinarily  high 
at  the  same  time.  This  may  be  considered,  then,  the  maximum  pos- 
sible stage  at  this  point. 

Since  that  time  the  conditions  have  been  very  materially  changed 
in  many  ways,  so  that  the  stage  at  the  present  time,  which  would  be 
equivalent  to  the  discharge  at  the  maximum  of  the  flood  of  1844, 
would  be  difficult  to  estimate.  The  flow  at  the  present  time  is  re- 
stricted to  a  narrow  channel,  while  in  1844  it  covered  the  bottom 
from  bluff  to  bluff  a  distance  of  several  miles. 

At  the  same  time  the  capacity  of  the  channel  proper  at  high  water 
is  very  largely  increased  by  the  use  of  present  artificial  embankments 


84  CHICAGO    METEOROLOGICAL   CONGRESS. 

that  concentrate  the  waters  and  increase  their  scouring  capacity. 
As  this  effect  varies  with  the  magnitude  and  duration  of  the  flood, 
it  is  very  difficult  to  measure.  The  maximum  amount  is  reached 
when  the  scour  reaches  bed  rock,  which  it  did  at  the  Merchants  Bridge 
during  the  flood  of  1892.  This  scour  was  more  than  20  feet  deep)  in 
some  places,  and  the  channel  capacity  was  nearly  or  quite  doubled. 
This,  the  greatest  known  flood  near  the  junction  of  the  Upper  Mis- 
sissippi and  Missouri  rivers,  does  not  seem  to  have  caused  excessively 
high  water  in  the  Lower  Mississippi.  The  maximum  stage  of  that 
year  at  Vicksburg  was  several  feet  lower  than  other  years,  and  oc- 
curred several  days  prior  to  the  maximum  stage  at  Saint  Louis ;  hence, 
could  not  have  been  materially  influenced  by  it. 

Referring  again  to  Plate  ii,  we  see  that  Cairo  is  situated  at  the  junc- 
tion of  the  Ohio  and  Mississippi  rivers.  The  drainage  basin  of  the 
Ohio  and  its  tributaries  is  207,100  square  miles.  The  Mississippi  and 
Missouri  basins  above  Cairo  comprise  707,300  square  miles,  or  a  total 
above  Cairo  of  914,400  square  miles. 

During  the  years  1882,  1883,  and  1884  the  average  discharge 
amounted  to  650,000  cubic  feet  per  second.  The  river  has  an  extreme 
range  of  53  feet  between  high  and  low  water. 

An  inspection  of  Plate  iii  shows  beyond  question  where  the  floods 
of  the  Lower  Mississippi  come  from.  The  great  floods  on  the  Ohio 
begin  in  February  and  have  passed  on  down  long  before  the  floods 
of  the  Missouri  and  the  Upper  Mississippi  reach  the  mouth  of  the 
Ohio.  The  only  exception  was  in  1875,  when  a  flood  from  the  Mis- 
souri on  August  1  was  joined  at  Cairo  by  a  moderate  flood  from  the 
Ohio  River.  This  caused  an  overflow  down  as  far  as  Lake  Provi- 
dence. The  maximum  stage  at  the  latter  point  occurred,  however, 
some  three  months  prior  to  the  arrival  of  the  Missouri  wave. 

The  floods  of  the  Missouri  and  Upper  Mississippi  rivers  have  never 
been  of  such  volume  as  to  become  a  serious  menace  by  themselves  to  the 
Lower  Mississippi  Valley,  and  as  they  never  come  in  conjunction  with 
one  another,  or  with  the  great  floods  of  the  Ohio  and  its  chief  tribu- 
taries, they  have  but  little,  if  any,  influence  on  the  flood  planes  of 
the  Lower  Mississippi  River. 

Thus,  the  startling  statement  that  an  acre  reclaimed  from  the  arid 
deserts  of  Montana  by  means  of  reservoirs  will  reclaim  another  acre 
from  the  floods  in  Louisiana  is  seen  to  be  wholly  lacking  in  the 
essential  elements  of  fact. 

After  passing  the  Ohio  the  volume  of  the  Mississippi  River  at  flood 
stages  is  often  increased  by  floods  from  the  tributaries.  The  White 
in  1892  added  181,000  cubic  feet  per  second,  the  Arkansas  400,000 
cubic  feet  per  second,  and  the  Red  River  183,000  cubic  feet  per  second. 
A  coincidence  of  floods  in  all  of  these  streams  may  occur,  and  the 


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(  FLOOD    PLANES   OF    THE    MISSISSIPPI.  85 

high  stages  of  the  Lower  Mississippi  are  thus  augmented  and  pro- 
longed. 

The  stages  below  Memphis  have  been  modified  by  the  renewal  of 
the  levee  system,  which  was  actively  begun  in  1883,  and  the  result  is 
that  the  maximum  stages  of  the  period  in  this  reach  have  occurred 
during  the  last  few  years. 

The  maximum  stage,  where  the  floods  are  confined  by  levees,  also 
depends  on  the  number  of  crevasses  which  occur,  and  hence  the  gauge 
reading  in  itself  may  be  rather  misleading  as  a  measure  of  the  mag- 
nitude of  the  flood.  In  addition  to  the  gauge  readings  it  is  important 
to  know  the  discharge  of  the  crevassees,  and  study  their  effect  on 
stage  from  the  first  break  until  they  reach  their  maximum. 

Plate  IV  is  a  hydrograph  of  the  Mississippi  River,  the  Missouri 
River  at  Hermann,  and  the  Ohio  River  at  Paducah.  It  gives  a  con- 
tinuous graphical  record  at  various  points  for  a  period  of  twenty-one 
years,  from  1872  to  1892,  inclusive.  The  horizontal  lines  represent 
differences  in  stage  of  one  foot.  The  bottom  line  of  each  hydrograph 
is  the  lowest  stage  reached,  and  the  top  line  is  the  highest  stage  reached 
during  the  period  1872-'92.  Hence,  the  depth  of  the  horizontal  lines 
gives  a  measure  of  the  extreme  oscillation  during  that  period  The 
scales  at  the  end  of  each  hydrograph  represent  the  gauges  as  read, 
their  zeros  being  sometimes  above  extreme  low  water  and  sometimes 
below. 

The  highest  and  lowest  gauge  readings  at  each  station  are  also 
shown  in  figures.     The  vertical  spaces  represent  months  and  years. 

The  full  irregular  line  follows  the  oscillation  in  stage  and  repre- 
sents a  continuous  daily  record  of  stage  at  each  station. 

The  dotted  horizontal  lines  show  the  bank-full  stage  and  its  rela- 
tions with  the  floods  of  each  year. 


86 


CHICAGO    METEOROLOGICAL    CONGRESS. 


Table  of  highest  annual  stages  and  their  dates  and  number  of  days  above  overflow  stage 
during  the  years  1872  to  1893. 


Hermann. 
(Missouri  River.) 


Hannibal.  i  Saint  Louis. 

(Upper  Mississippi  River.)  |  (Middle  Mississippi  River.) 


Year. 


1872  . 

1873  • 
1874. 
J875 
1876, 
1877. 
1878, 
1879. 

1880  , 

1881  . 
1882, 
188}, 

I88:^. 

1885. 
1886. 
I&87. 
1888. 
I8S9. 
1890  , 

1891 . 

1892 , 

1893. 


Feet. 


June  10 12.6 

June  19 13.2 

Aug.  I 18.6 

July  6 19.6 

June  13-14.,  19.1 

July9 15-2 

June  29 16.2 

July  15 13-4 

May  4 20. 4 

July  3 18.9 

June  24 21. 1 

May  6 1  14.8 

June  21 1  18.5 

May  12 15.2 

June  16 14.4 

July  I 16.8 

May  30 16.4 

Apr.  4 II. 5 

July3 17.2 

May  15 23-0 

June  26 ,  19.3 


»  ®  a, 

£22 

g  oi  IK 


June  9. 

May  12 
Mar.  13 


Mean.... |  16.9 


o     June  3.. 

o     July  3  .. 

8     Oct.  27.. 

7  July  2  .. 
19?   May  20  . 

o  '  Apr.  30.. 
16  I  Mar.  16  . 

o     May  9  .. 

o  i  Feb.  13  . 

o     May  17  . 

o  I  June  9.. 

o     July  3  .. 

-,  Apr.  23  . 
July  3  .. 
May  27.. 


24 


Feet. 
13-3 
14-5 
10.2 


»  S  ® 

s  9  =5 


10.6 

0 

T8.7 

2S 

20.6 

155 

18.4 

102 

17.6 

68 

18.5 

53 

13.2 

II 

17. 1 

82 

12.0 

0 

21.6 

70 

8-3 

0 

13-5 

12 

12.2 

3 

20.8 

89 

16.3 

June  12-14.. 

Apr.  II 

June  19-20.. 

Aug.  3 

May  10 

June  14 

June  15 

July  3 

July  12 

May  6 

July  5-6  .... 

June  26 

Apr.  9-10.... 

June  17 

May  13 

Apr- 3 

June  4 

June  I 

July  I 

Apr.  25 

May  19 

May  3 


15-4 


O 


<M  q 


®  2  « 

S  c3  a 


Feet. 
23-0 
25-5 
18.4 
29.8 
32.0 
26.6 
25-7 

21.2 
25-5 

33-7 
32.2 
34-8 
28.1 
27.1 
27.0 
20.7 

29-3 
24.6 
20.6 
23-4 
36.0 
31.6 


27.1 


Year. 


Paducah. 
(Ohio  River.) 


1872  . 
1873. 
1874. 
1875. 
1876. 
1877. 


Feet. 


1879. 

1880  . 

1881  , 
1882. 
1883. 
1884  . 
1885. 
1886  . 
1887, 
1888. 

1889  • 

1890  , 

1891  . 

1892  . 
1893. 


Mar.  23  . 
Feb.  5  . , 
Jan.  27.. 

Mar.  18  . 
Jan.  25.. 
Mar.  22  . 
Feb.  24. . 
Feb.  26. . 
Feb.  25. . 
Feb.  23. . 
June  25. 
Apr.  17.. 
Mar.  8  . . 
Apr.  5  . . 
Feb.  26  . 
Mar.  II  . 
Mar.  I  •. . 
Apr.  29.. 
Feb.  27.. 


44.0 
44.9 
38.8 

28.7 
38.8 
44.0 
40.6 
50-0 
.so.  7 
54-2 
38-0 
50-4 
46.8 
40.6 
31-4 
48-5 
45-5 
42.9 

44-3 


Mean 43.3 


.0 

0)  «  aJ 

.c  >  60 

S  fli  K 


Cairo. 
(Middle  Mississippi  River. 


46 


Helena. 
(Lower  Mississippi  River.) 


Apr.  19. 
Feb.  26. 
Apr.  26 
Aug.  8  . 
Apr.  6.. 


(B  g  © 
.Q  >  60 

S  cS  ai 


41 

47 
45 

;  46 
Apr.  15 4a 


Apr.  29 

Dec.  31 

Mar.  22 

Apr.  20 

Feb.  26 

Feb.  27 

Feb.  22-24. 
Jan.  26.... 
Apr.  19.... 
Mar.  9-10  . 
Apr.  4  .... 
June  24... 
Mar.  12  ... 
Mar.  4-6  . . 
Apr.  28  ... 
May  9 


Feet. 
39-2  1 

4 
I 

4 
5 


45 

4 

35 

4 

48 

8 

46 

2 

48 

3 

49 

3 

45 

I 

Apr.  26 

Mar.  6 

May  II  

Apr.  12-14... 
Apr.  18-19... 
Apr.    30    to 

May  I. 
May  3-4  . , . , 

Jan.  31 

Mar.  31 

May  14 

Mar.  9 

Mar.  8-9 

Mar.  6 

Jan.  30 

Apr.  30 

Mar.  21-22  .. 
Apr.  14-15- •■ 

June  28 

Mar.  28-30  . . 
Mar.  26-28  . . 
May  11-12  .. 
May  25 


O 


Feet. 

39-0 
40.0 
45-8 
42.4 
44.8 
41.8 

38-7 
37-2 
43-7 
43-7 
47.2 
46.9 
47.0 
40.7 
48.1 
46.4 
42.8 
34-1 
47-7 
44-7 
45-7 
48.0 

43-5 


O  es 

«  ®  4, 
.0  ^  at 

sSs 

9  03  CO 
25 


FLOOD    PLANES    OF    THE    MISSISSIPPI. 

Table  of  highest  annual  stages,  etc. — Continued. 


87 


Year. 


Lake  Providence. 
(Lower  Mississippi  Kiver. ) 


Red  River  Landing. 
(Lower  Mississippi  River.) 


O 


C8\S 

v.  c 

O  C5 

.a 

JO  »  5, 

all 

S  oi  m 


60 


O 


©  2  ® 

S  2  03 

3  c8  OJ 

Z 


Carrollton,  La. 
(Lower  Mississippi  River.) 


O 


2  2  * 

S  c3  n 


1872 
1873  • 
1874 
1875  • 

1876, 

1877 

1878, 

1879 

1880. 

18S1 

1882 

1883 

1884  . 

1S85, 

1886, 


1890  . 

1891 

1892 
1893 


May  I  .... 
May  28  . . . 
Mar.  21-23 
Apr.  19-20. 

Apr.  12-14. 
May  6-7  . . 
Mar.  22-24 
Feb.  14-16. 
Apr.  3  . . . . 
Mar.  II  ... 
Miir.  20  ... 
Mar.  11-14 
Mar.  23-24 
May  10- 1 1 
May  7  . 
Mar.  26 
Apr.  24-25 
July  I  , 
Mar.  15 


Mar.    31  to- 

Apr.  4. 
June  2 

May  16-17  •• 


Feet. 

35-1 
36. 1 
37-4 
37-3 

37-9 

35-8 
35-8 
36.0 
38.0 
36.2 
38-3 
36-5 
38-4 
35-5 
37-9 
38-0 
38-1 
29.4 
41.0 


41.0 

11.9 

41.8 

37-4 

15 

o 

102 

70 
83 


May  6  . . 
June  12. 
Apr.  16  . 

May  3  .. 


May  15  . .., 
June  1-3... 

Mar  — 

Feb.  19-20.. 
Apr.  22-24., 

Apr.  6-9 

Mar.  27 

:\Pr-9 

Mar.  29-31 . 
Feb.  5-6. . . . 

May  31  

Apr.  8 

Ai)r.  30  . . . , 
Mar.  13-15  . 
Apr.  23 


Feet. 

39-4 
39.0 
47.0 
40.4 

45-4 
40-5 


Apr.    26   to 
May  4. 

June  27 

June  24 


35-9 
44.0 
40. 1 
48.5 
45-2 
47-3 
42.0 
41.9 

43-0 
41.7 

33-9 
48.6 

45-5 

48.9 

47-7 


75 


101 
70 
92 


May  6 

June  3-4... 
Apr.  16 

May  3-5, 14, 

16-18. 

May  II  

June  4-8... 

Mar.  21 

Feb.  20-22.. 
Apr.  23-24  . 

Abr.  12 

Mar.  27  . . . . 
Apr.  7....'.. 

Mar.  iS 

Jan.  22-23  • 

May  31 

Apr.  6-9  . . . 

Apr.  26 

Mar.  13-14  . 
Mar.  14, 15, 

16, 17-22 
Mar.  16 


June  10 

June  23-25. 


Feet. 
12.3 
12.9 
15-7 
"•3 

12.7 
II. I 
"•3 
10.8 
14.2 
12.5 
14.9 
15-4 
15-6 
13-5 
13-8 
14-5 
14-3 
"•5 
16.0 

i5.  o 

17-3 
17-1 


80 

i9§ 

147 
119 

59 
74 
56 
37 
o 
136 


88 


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187 1. 


RIVER   STAGE    PREDICTIONS. 

Table  of  high  water  prior  to  1872. 


89 


Year. 


Saint  Louis. 


Cairo. 


Date,    j  Stage.       Date.      Stage 


June  28 


June 
June 


.\pr. 
May 
May 
July 
Apr. 
Mar. 


Feet. 


36-4 
41.4 


36-7 
37-1 


31-4 
28.2 
24.2 

29-3 
26.2 

21.8 


Apr. 


June  21 
May  7 
May  2 
Mar.  21 
May   19 


F^t. 
51.6 
47.6 


49.6 
46.5 
50-8 
51-0 
45-6 


Memphis. 


Date. 


July  — 
May  14 
Mar.  II 
June  23 
May    12 


Stage. 


Feet. 


32-7 
33-0 

33-4 
33-0 
34-0 
33-9 


Mar.  26 


33-9 


Helena. 


Date. 


May 


Stage. 


Feet. 


July    2 
Mar.  22 


43-1 
42.2 

42.8 
39-8 
44.6 
43-6 
46.4 
45-8 


Vicksburg. 


Natchez. 


Year. 


Date. 


Stage. 


Date. 


Baton  Rouge. 


Stage.       Date. 


Carrollton. 


Stage.        Date. 


Stage. 


1809. 
1811. 
1813. 
1815. 
1823. 
1824. 
1828. 
1844. 
1850. 
185:. 
1858. 
1859. 
1862. 
1867. 
1868. 
1869. 
1870. 
1871. 


Feet. 


June  26 
June    4 


June  26 
Apr.  21 
Apr.   27 


46-3 
46.1 
47-0 


46.9 
48.2 
51- 1 
49.0 


May 
June 
June 
June 
May 
May 
Mar. 
July 


Apr. 
June 
May 


Feet. 
46.9 
47.0 
48.2 
49.2 
48.3 
47-8 
48.8 
47-9 
47-3 
47-1 
47-8 
49.0 
49-9 
47-9 
43-9 
46. 1 

44-3 
43-8 


Mar.  15 
Apr.     I 


May     6 


Feet. 


34-7 
33-9 

34-5 
34-5 
34-5 
35-0 
36.1 


Feet. 


Apr. 


Jan.  21 
Mar.  27 
May  10 
May     4 


15-2 

14-5 
13-8 
15-4 
15- 1 
15-6 
15-9 


34-5 


34-5 


15-4 


3.— RIVER  STAGE  PREDICTIONS  IN  THE  UNITED  STATES. 

Thomas  Russell. 

The  river  service  of  the  United  States  Weather  Bureau  has  191 
river  gauges,  mostly  at  large  cities  on  the  principal  rivers  throughout 
the  country.  A  record  is  kept  of  the  daily  stages  of  ihe  water  in  the 
interest  of  low  water  navigation  and  for  flood  warnings.  Besides  the 
Weather  Bureau  gauges  others  are  maintained  along  the  Mississippi 
and  Missouri  rivers  by  the  Mississippi  and  Missouri  River  Com- 
missions in  the  interest  of  river  improvements  that  are  being  made. 

A  river  gauge  consists  of  a  plank  about  a  foot  wide  and  of  sufficient 
length  to  include  the  range  of  water  from  low  to  high  water,  and  is 
marked  to  feet  and  tenths  of  a  foot.  It  is  fastened  to  a  bridge  pier, 
where  one  is  available,  or  it  may  consist  of  a  narrow  strip  of  a  stone 
pier  dressed  down  to  a  smooth  surface  to  receive  the  marking  and 
numbering.     Where  there  is  no  bridge  pier  available,  a  gauge  is  made 


90  CHICAGO    METEOROLOGICAL   CONGRESS. 

of  heavy  timbers,  6  by  12  inches,  laid  along  the  incline  of  a  river 
bank,  with  a  strip  of  iron  fastened  along  the  top  for  the  marking.  A 
gauge  is  placed  with  the  zero  of  graduation  at  the  level  of  the  lowest 
water  as  near  as  possible.  The  marks  indicate  vertical  heights  of 
the  water  surface  above  low  water.  The  gauge  readings  are  called 
stages.  The  stages  read  daily  at  8  a.  m.  are  telegraphed  to  various 
places  interested  in  information  as  to  the  stages  of  rivers.  At  a 
number  of  the  larger  cities  throughout  the  country  a  river  bulletin, 
in  connection  with  the  weather  maps,  is  issued  daily  from  the 
Weather  Bureau  offices. 

At  high  water  when  there  is  danger  of  a  river  overflowing  its  banks 
the  observations  of  stages  are  of  interest  to  districts  liable  to  be 
flooded.  To  places  where  definite  information  of  the  extent  of  a 
coming  high  water  can  be  given  warnings  are  sent  by  telegraph. 

The  highest  water  in  a  freshest,  or  the  crest  stage,  occurs  first 
toward  the  head  waters  of  a  river.  After  a  flood  wave  forms  there  is 
a  progressive  motion  of  the  crest  down  stream  at  the  rate  of  three  or 
four  miles  per  hour.  This  renders  it  possible  to  form  some  idea  of 
what  the  highest  stages  of  water  will  be  along  the  lower  course  of 
a  river  from  the  stages  along  the  upper  course.  Better  predictions  of 
high  stages  can  be  made  the  greater  the  length  of  record  on  which 
to  base  a  rule  for  prediction.  Accurate  predictions  of  river  stages 
at  low  water  are  not  possible.  Where  the  discharges  of  a  river  for 
low  stages  are  known,  that  is,  the  quantity  of  water  passing  through 
the  river  for  different  stages  near  low  water,  estimates  can  be  made 
ahead  of  stages  below  which  the  river  will  not  fall ;  but  the  least  fall 
of  rain  after  the  prediction  is  made  makes  the  river  rise  at  low  stages 
very  rapidly. 

At  high  water  predictions  of  stages  are  made  in  various  ways, 
depending  on  the  nature  of  the  rivers. 

In  the  case  of  two  places  on  the  same  stream,  the  gauge  readings 
are  more  or  less  closely  dependent,  according  as  the  distance  between 
them  is  less  or  greater.  The  gauge  readings  follow  each  other  more 
closely  in  a  rise  the  less  the  quantity  of  w^ater  coming  into  the  river 
from  the  drainage  area  between  them.  Predictions  of  the  lower  stage 
from  the  upper  one  can  be  made  more  accurately  the  less  the  propor- 
tion of  the  drainage  area  between  the  two  places  bears  to  the  whole 
drainage  area  above  the  lower  place. 

The  character  of  a  river  varies  greatly  along  its  water  course  as  to 
slope  and  width.  Though  two  places  on  the  same  stream,  a  hundred 
miles  or  so  apart,  may  have  nearly  the  same  quantity  of  water  pass- 
ing them,  the  stage  at  one  of  them  may  be  twice  as  high  as  at  the 
other,  the  difference  being  made  up  by  the  greater  width  of  the  river 
or  the  greater  velocity  of  the  water  at  the  one  as  compared  with  that 
of  the  other.     At  Louisville,  for  instance,  on  the  Ohio  River,  132 


RIVER    STAGE    PREDICTIONS.  91 

miles  below  Cincinnati,  the  drainage  area  above  it  is  84,600  square 
miles.  The  drainage  area  above  Cincinnati  is  71,300  square  miles. 
The  record  of  stages  shows  that  the  highest  water  at  Louisville  occurs 
about  one  day  after  the  highest  water  at  Cincinnati.  By  taking  the 
means  of  groups  of  crest  stages  at  Cincinnati  for  stages  about  five 
feet  apart,  and  the  means  of  subsequently  occurring  crest  stages  at 
Louisville,  the  following  corresponding  stages,  in  feet,  for  the  two 
places  are  obtained : 

Cincinnati... 40        45         50         55         60        65         70 

Louisville 17         20         26         32        38        43         46 

This  table  is  used  for  predicting  the  stage  crest  at  Louisville  when 
the  highest  water  at  Cincinnati  is  known,  or  when  it  can  be  estimated 
closely  from  previously  occurring  high  stages  at  points  above  it. 

For  a  place  where  a  rise  in  the  river  is  the  result  of  rises  in  com- 
paratively large  tributary  rivers,  the  best  method  of  deriving  a  rule 
for  stage  prediction  is  by  the  comparison  of  the  rises  at  the  place 
with  the  preceding  rises  at  places  on  the  streams  above  it.  The  prin- 
ciple on  which  a  rule  for  prediction  is  derived  in  such  a  case  is  as 
follows,  in  the  case  of  Cairo.  111.,  for  example:  At  Cairo,  111.,  near 
the  mouth  of  the  Ohio  River,  a  rise  may  be  the  result  of  a  rise  at 
any  or  all  of  the  following  places:  at  Saint  Louis,  on  the  Mississippi 
River,  168  miles  above  the  mouth  of  the  Ohio  River ;  at  Mount  Car- 
mel.  111.,  on  the  Wabash  River,  178  miles  above  Cairo;  at  Evansville, 
Ind,,  on  the  Ohio  River,  183  miles  above  Cairo ;  at  Nashville,  Tenn., 
on  the  Cumberland  River,  215  miles  above  Cairo ;  at  Johnsonville, 
Tenn.,  on  the  Tennessee  River,  140  miles  above  Cairo. 

The  drainage  area  above  Saint  Louis  is  699,000  square  miles.  Th3 
quantity  of  water  passing  in  the  river  at  the  lowest  stage  is  48,000 
cubic  feet  a  second;  at  the  highest  stage,  which  is  36  feet,  1,146,000 
cubic  feet  a  second.  Above  Mount  Carmel  the  drainage  area  is  26,000 
square  miles,  the  discharge  at  the  lowest  stage  14,000  cubic  feet  a 
second,  and  at  the  highest,  28  feet,  220,000  cubic  feet.  Above  Evans- 
ville the  drainage  area  is  99,700  square  miles,  the  low  water  discharge 
is  60,000  cubic  feet  a  second,  and  at  the  highest  stage,  49  feet,  about 
660,000  cubic  feet  a  second. 

The  drainage  area  above  Nashville  is  11,600  square  miles,  the  low 
water  discharge  is  7,000  cubic  feet  a  second,  and  at  the  highest  stage, 
58  feet,  160,000  cubic  feet  per  second. 

Above  Johnsonville  the  drainage  area  is  36,700  square  miles,  the 
low  water  discharge  is  33,000  cubic  feet  a  second,  and  at  the  highest, 
48  feet,  about  450,000  cubic  feet. 

At  Belmont,  Mo.,  on  the  Mississippi  River,  20  miles  below  Cairo, 
the  low  water  discharge  is  176,000  cubic  feet  a  second,  and  the  high 
water  discharge,  corresponding  to  a  52-foot  stage  at  Cairo,  is  about 
1,603,000  cubic  feet. 


92  CHICAGO    METEOROLOGICAL    CONGRESS. 

A  rise  at  one  of  the  up-river  stations  has  more  effect  in  producing 
a  subsequent  rise  at  Cairo  the  greater  the  length  of  time  the  higher 
stage  lasts  at  the  up-river  station.  The  continuation  of  the  higher 
stage  beyond  three  days  has  no  effect  in  increasing  the  rise  at  Cairo 
For  a  less  continuation  than  three  days,  the  rise  at  Cairo  is  a  pro- 
portional part  of  the  greatest  rise  that  takes  place  for  a  three-day 
continuation  of  the  high  stage. 

From  a  consideration  of  the  slopes  of  the  river-surfaces  between 
Cairo  and  the  up-river  stations  for  different  stages  at  the  various 
places  from  low  to  high  water,  and  the  varying  cross-sections  and 
depths  for  the  different  stages  at  the  various  places,  the  ratio  of  a 
one-foot  rise  at  the  various  places  to  the  corresponding  rises  at  Cairo 
is  derived  theoretically,  as  far  as  the  data  will  permit,  taking  into 
account  the  extent  of  cross-section  and  the  velocity  of  water  as  af- 
fected by  different  depths  and  slopes. 

A  comparison  of  the  theoretical  rises  thus  obtained  with  the  rises 
actually  observed  in  cases  for  which  there  are  records,  gives  a  factor 
for  each  place  for  certain  stages.  Only  a  few  of  the  possible  cases 
that  can  occur  have  ever  been  observed. 

The  record  of  stages  at  Cairo  and  the  up-river  stations  is  too  short, 
as  yet,  to  furnish  cases  of  all  the  possible  variety  of  combination  of 
freshet  wave  crests  from  the  various  rivers  which  produce  a  high 
water  at  Cairo.  For  the  possible  cases  which  may  occur  in  the  future, 
but  of  which  there  are  no  observations  as  yet,  the  theoretical  value  of 
the  rise  found  as  described  is  multiplied  by  a  factor  derived  for  the 
stages  at  which  there  have  been  actual  observations  of  rise.  In  this 
way  tables  are  prepared  which  show  the  relation  of  a  one-foot  rise  at 
the  various  places  to  the  subsequent  rise  in  three  or  four  days  at 
Cairo,  that  being  the  crest-wave  time  between  Cairo  and  the  various 
places.  The  rise  at  Cairo  is  taken  as  the  sum  of  the  various  com- 
puted rises  at  the  five  places. 

In  case  of  a  fall  at  any  of  the  places  instead  of  a  rise,  it  enters  the 
sum  with  a  minus  sign. 

The  stage  that  will  prevail  at  Cairo  can  be  estimated  six  to  seven 
days  ahead  from  the  stages  at  Cincinnati,  Chattanooga,  and  Saint 
Louis,  with  allowance  for  the  water  coming  out  ©f  the  Cumberland 
and  Wabash.  But  as  the  cross-sections  at  Cincinnati  and  Chatta- 
nooga are  not  known,  the  rule  for  prediction  of  stages  has  to  be  based 
on  the  comparison  of  actually  observed  rises. 

In  cases  where  the  discharges  and  cross-sections  of  rivers  at  places 
are  not  known,  some  idea  can  still  be  formed  of  the  relative  impor- 
tance of  different  tributaries  in  causing  a  rise  at  a  point  on  a  main 
stream,  provided  there  is  a  long  record  of  stages  with  rises  at  the 
lower  point  due  to  rises  sometimes  in  one  of  the  tributaries  and 


RIVER    STAGE    PREDICTIONS.  93 

sometimes  in  another.  This  permits  of  estimating  the  effect  of  each 
separately. 

A  rise  at  a  high  stage  of  a  river  has  more  effect  than  an  equal  rise 
at  a  low  stage  in  producing  a  rise  at  a  point  lower  down  the  river. 
On  the  other  hand,  the  higher  the  stage  at  the  lower  point  the  less 
the  effect  of  a  rise  at  an  up-river  point  in  producing  a  rise  below. 

The  products  of  the  rises  by  the  mean  stages  during  the  rises  are 
taken  as  comparable  throughout  the  range  of  stages  at  the  place. 
For  very  high  stages  this  does  not  hold  good.  Where  a  river  over- 
flows its  banks  and  becomes  miles  in  width,  very  great  rises  at  up- 
river  stations  have  very  little  effect  in  producing  a  further  rise  below, 
and  it  is  impossible  to  estimate  effects  in  such  cases. 

In  some  cases  the  extent  of  the  drainage  areas  above  up-river 
gauge  stations  is  taken  into  account  in  devising  a  rule  for  predicting 
a  high-water  stage  at  a  lower  point.  In  a  case  of  this  kind  at  Pitts- 
burg, the  prediction  is  based  on  the  stages  at  the  following  places 
above  it : 

Sq.  miles. 

Oil  City 4,526 

Brookville 400 

Confluence 782 

Rowlesburg 886 

Weston 140 

Johnstown '. 711 

The  effect  of  a  rise  at  a  place  in  producing  a  rise  at  Pittsburg  is 
taken  as  proportional  to  the  square  root  of  the  area  above  it.  The 
whole  area  above  Pittsburg  is  17,000  square  miles.  The  areas  above 
the  six  places  comprise  7,445  square  miles  of  the  area  above  Pitts- 
burg. The  rise  at  Pittsburg  multiplied  by  the  mean  stage  during  the 
rise,  and  by  an  unknown  factor  for  a  number  of  selected  cases  of 
great  rise,  are  placed  equal  to  the  sums  of  the  rises  at  the  six  places 
above,  weighted  according  to  the  square  root  of  the  drainage  areas 
above  them,  the  unit  of  area  being  taken  as  1,000  square  miles.  From 
these  the  value  of  the  unknown  factor  is  derived.  With  the  factor  a 
table  is  prepared  which  gives  the  highest  stage  at  Pittsburg  when  the 
rises  at  the  upper  gauge  are  known. 

Gauge  readings  at  a  place  made  on  successive  days,  or  at  intervals 
a  few  hours  apart,  during  a  rise  are  of  some  service  as  indicating  how 
high  the  water  may  be  expected  to  go.  The  characteristic  of  a  rise 
for  most  places  is  that  the  rate  of  rise,  small  at  first,  gradually 
increases  as  the  rise  continues,  until  a  maximum  rate  is  attained, 
and  then  diminishes  until  it  becomes  zero  at  the  crest  stage.  The 
characteristic  variations  in  rate  of  rise  vary  greatly  in  different 
places,  depending  largely  on  the  slopes  of  the  ground  over  the  drain- 
age area  and  on  the  customary  distribution  of  rainfall.  As  a  rule,  the 
characteristics  of  a  rise  are  more  permanent  or  more  nearly  alike  in 


94  CHICAGO    METEOROLOGICAL    CONGRESS. 

different  rises  the  greater  the  drainage  area  above  a  place.  At  Cin- 
cinnati, for  example,  on  the  Ohio  River,  the  rate  of  rise  begins  to 
diminish  on  the  average  about  three  days  before  the  crest  stage  is 
reached.  This  is,  therefore,  a  useful  criterion  in  judging  how  long 
the  river  will  continue  to  rise.  The  observed  rate  of  rise  can  be  used 
to  estimate  a  stage  for  some  time  ahead.  This  is,  however,  mostly 
an  uncertain  method,  and  only  to  be  used  where  other  methods  are 
not  available. 

In  some  cases,  where  there  is  only  a  single  gauge  on  a  river  and 
the  drainage  area  above  it  is  small,  the  reliance  in  making  predic- 
tions must  be  wholly  on  observations  of  the  depth  of  rainfall  over 
the  area.  Definite  stage  predictions  are  out  of  the  question  in  such 
cases,  and  the  most  that  can  be  said  is  that  a  very  high  stage  will 
prevail  when  the  rainfall  over  the  area  is  seen  to  exceed  a  certain 
amount  for  the  average  of  a  number  of  stations. 

As  an  example  of  this  it  requires,  at  the  least,  a  rainfall  of  3  inches 
in  less  than  three  days  over  the  15,000  square  miles  of  drainage  area 
of  the  Potomac  River  to  raise  the  stage  at  Harpers  Ferry  to  34  feet, 
which  corresponds  to  12  feet  at  Washington,  D.  C,  twelve  hours  later. 

Over  the  Savannah  River  drainage  area  of  7,500  square  miles  it 
requires  a  rainfall  of  5  inches  in  three  days  to  cause  the  river  to  rise 
at  Augusta,  Ga.,  to  the  highest  stage  known,  which  is  38.7  feet. 


4.— METHODS  IN  USE  IN  PRANCE  IN  FORECASTING  FLOODS. 

M.  Bauinet. 

Historical. — In  requesting  M.Georges  Lq  jnoine,  In  genieur  en  chef  des 
Pouts  et  Chaussees,  Paris,  to  present  a  paper  on  the  methods  in  use 
in  France  in  forecasting  floods,  for  the  International  Congress  of 
Meteorology  to  meet  at  Chicago  in  August,  1893,  the  Honorable  Chair- 
man of  the  Section  devoted  to  Rivers  and  Floods  kindly  remarks  that 
the  idea  of  predicting  the  level  of  rivers  originated  in  France,  and 
that  questions  of  this  nature  have  been  treated  there  with  more  care 
than  elsewhere. 

It  was  in  1854  that  the  illustrious  Belgrand  organized  a  network  of 
permanent  hydrometric  observations  in  the  basin  of  the  Seine.  He 
derived,  a  short  time  after,  a  preliminary  rule  for  the  forecasting  of 
floods  at  Paris ;  about  the  same  time  similar  investigations  yielded 
appreciable  results  on  other  French  rivers  better  naturally  disposed, 
without  doubt,  to  facilitate  the  forecasts.  M.  Camoy  tried  to  predict 
the  floods  of  the  Loire  at  Orleans  and  Tours  from  observations  made 
at  points  above  and  below  as  far  as  the  confluence  of  the  Allier,  below 
which  the  Loire  receives  no  important  affluent  throughout  300  kilo- 
meters of  its  length.      M.  Poincar^  did  the  same  for  the  Meuse,  the 


FORECASTING    FLOODS.  96 

situation  of  which  is  similar,  from  the  place  where  it  leaves  the  De- 
partment of  the  Vosges  to  its  entrance  into  the  Ardennes. 

The  relation  of  cause  and  effect  which  attaches  to  the  swelling  of 
certain  rivers  in  the  principal  stream  of  which  they  are  tributaries 
must  have  previously  attracted  the  attention  of  some  bright  minds. 
It  was  known  that  heavy  rains,  especially  in  mountainous  regions, 
could,  by  their  accumulation  and  the  simultaneousness  of  their  pro- 
gressive flow  through  the  plains,  produce  inundations  at  points  lower 
down. 

But  the  possibility  of  analyzing  in  every  case  these  complex  phe- 
nomena and  extracting  from  them  information  of  practical  value  had 
not  been  demonstrated  before  the  investigations  of  Belgrand.  His 
fundamental  work  (La  Seine,  regime  cle  la  pluie,  des  sources,  des  eaux 
courantes,  Paris,  chez  Dunod,  1873)  laid  the  foundation  of  a  new  sci- 
ence, hydrology,  of  which  the  forecasting  of  floods  is  but  an  interest- 
ing application. 

The  affluents  of  the  Seine  coming  from  permeable  soil  (oolite,  chalk, 
limestone),  rise  more  slowly  than  the  others.  Their  slopes  are  almost 
always  more  feeble ;  except  in  certain  exceptional  circumstances,  the 
absorption  of  water  by  the  ground  is  greater ;  the  superficial  flow  at 
the  start  is  a  matter  of  very  great  importance. 

These  considerations,  in  connection  with  very  complete  geological 
investigations,  have,  in  predicting  the  maximum  of  a  flood  at  Paris, 
permitted  of  neglecting  the  movement  of  the  upper  part  of  the  river 
above  the  confluence  of  the  Yonne,  in  spite  of  the  extent  of  the  basin, 
and  that  of  the  Aube  in  the  Jurassic  and  Cretaceous  formations. 
The  Yonne,  the  Marne,  and  their  principal  affluents,  are  all  that  it  is 
necessary  to  take  into  account. 

The  time  of  propagation  of  the  wave  crest. — The  rapidity  of  the  flow 
of  water  on  the  surface  of  impermeable  ground  does  not  permit  of 
making  forecasts  in  time  to  be  of  use  unless  the  observations  that 
serve  as  a  basis  are  made  at  a  great  distance  above.  Even  as  far 
below  as  Paris,  where  the  Seine,  full  formed,  is  far  from  having  a 
torrential  regime,  the  interval  of  a  wave  crest  at  two  stations,  with 
no  important  lateral  valley  intervening,  corresponds  frequently  to  a 
velocity  of  four  kilometers  an  hour,  if  not  more. 

In  1854  telegraphic  communication  was  not  so  perfected  as  to-day. 
A  whole  day  could  easily  be  lost  before  advices  could  be  received 
from  the  most  interesting  stations. 

This  was  the  reason  why  the  principal  points  of  observation  were 
chosen  by  Belgrand  toward  the  limits  of  the  higher  upper  imper- 
meable lands,  as  indicated  in  the  Manual  Hydrologique  du  Bassin  de 
la  Seine  (Imprimerie  Nationale,  1884,  p.  50). 

Prediction  of  floods  by  rises. — It  happens  frequently  that  several 
oscillations  close  together  in  a  water  course  in  the  upper  part  of  the 


96  CHICAGO    METEOROLOGICAL    CONGRESS. 

region  in  question  correspond  to  a  single  continuous  great  rise  of  the 
Seine  in  the  vicinity  of  Paris ;  it  is  a  multiple  wave  of  which  the 
maximum  does  not  depend  alone  on  the  highest  stages  prevailing  at 
the  points  above.  The  successive  waves  unite  below,  where  their 
velocity  slackens,  and  where  there  is  thus  a  very  great  accumulation 
of  water.  From  this  has  arisen  the  practice,  for  the  basin  of  the 
Seine,  of  considering  the  relation  of  rises  "of  which  the  name  alone  is 
scarcely  a  definition.  Even  in  the  case  of  simple  waves,  produced  by 
a  single  group  of  rains,  the  rise  (or  the  difference  between  the  level 
of  the  water  at  the  beginning  of  the  rise  and  when  the  highest  point 
is  reached)  has  the  advantage  of  being  independent  of  the  stage 
whence  it  starts,  if  it  is  not  artificially  influenced  by  a  movable  dam 
which  is  finally  lowered. 

Certain  rises  may,  moreover,  be  taken  as  representative  signs  or 
evidences  of  the  hydrological  phenomena  of  which  a  neighboring 
region  is  the  theater.  It  is  in  this  way  that  in  the  rule  for  announc- 
ing floods  in  the  Seine  at  Paris  Belgrand  was  able  to  make  use  of  the 
Aisne  at  Ste.  Menehould  and  the  Aire  at  Vraincourt,  even  though  the 
waters  of  these  two  rivers  run  into  the  Oise  and  have  not,  conse- 
quently, any  actual  influence  on  the  stage  as  read  from  the  gauge  on 
the  Austerlitz  bridge.  For  a  similar  reason,  in  order  to  take  into 
account  the  great  superficial  extent  of  the  basin  of  the  Marne,  in 
place  of  double  the  rise  taken  at  a  single  point  of  the  river  conven- 
iently chosen,  the  formula  for  prediction  at  Paris  contains  the  rise 
of  the  Marne  at  Chaumont  and  St.  Dizier,  one  of  which  precedes  the 
other  except  for  the  changes  due  to  the  intermediate  tributaries. 

Whatever  may  be  thought  of  the  principle  of  this  method,  it  is  in 
any  case  justifiable  by  the  excellence  of  the  results;  for  the  three 
great  floods  at  Paris  have  been  predicted  one  or  two  days  in  advance 
within  a  few  centimeters  of  the  correct  stage,  notably  those  of  March, 
1876,  and  February,  1889.  The  same  processes  have  been*  employed 
elsewhere  by  M.  G.  Lemoine  in  predicting  the  floods  of  the  principal 
tributaries  of  the  Seine,  as  may  be  seen  in  the  Manual  Hydrologique 
mentioned  above  (pp.  51-55). 

The  prediction  of  floods  by  rise  is  moreover  well  adapted  for  tak- 
ing into  account  certain  necessary  corrections  due  to  accessory  influ- 
ences ;  it  is  susceptible  of  improvement.  As,  for  instance,  when  at  a 
station  for  which  predictions  are  made  a  flood  occurs  when  the  stage 
is  falling,  that  is  to  say,  for  a  sufficient  length  of  time  before  the 
river  has  returned  to  the  normal  level  of  the  season,  the  rise  calculated 
by  the  ordinary  formula  ought  generally  to  be  reduced  in  a  certain 
proportion ;  a  part  of  the  water  is  used  in  a  manner  to  overcome  the 
tendency  toward  lowering,  or  is  absorbed  by  the  drawing  effect  of  the 
preceding  movement. 

The  rise  to  be  predicted  at  a  lower  station  may  moreover  be  a  dis- 


FORECASTING    FLOODS.  97 

continuous  function  of  those  at  points  above ;  it  is  therefore  highly 
probable  that  when  the  river  rises  above  the  level  at  which  in  a 
number  of  places  the  wetted  perimeter  of  a  cross-section  increases 
sharply  for  a  slight  increase  of  height  (flood  levels)  these  anomalies 
are  less  appreciable  than  at  principal  stations,  where  the  phenomena 
occurring  in  a  great  basin  proceed  more  regularly ;  for  reasons  of  the 
same  nature  they  are  less  to  be  feared  than  more  important  floods. 
If  the  announcement  of  slight  changes  is  of  any  interest  on  second- 
class  rivers,  floods  may  be  classified  by  families  according  to  the  ini- 
tial stages  or  the  magnitudes  of  the  rises  and  a  special  formula  may 
be  used  for  each  kind.  This  has  been  tried  recently  for  some  stations 
in  the  basin  of  the  Oise. 

Announcement  of  floods  by  absolute,  stages. — The  study  of  stages,  very 
extensive  in  the  basin  of  the  Seine,  of  which  the  hydrologic  compli- 
cation is  sufficiently  great,  is  not  so  generally  in  use  on  the  other 
French  rivers  where  the  situation  is  different. 

On  the  Seine  itself  where,  on  the  tributaries,  without  giving  up  t^e 
method  of  predicting  by  rises  which  generally  permit  of  making 
predictions  a  sufficient  length  of  time  ahead,  it  has  been  possible 
in  the  last  fifteen  or  twenty  years,  especially,  to  utilize  the  exten- 
sion of  the  telegraph  for  obtaining  in  time  information  as  to  the 
stages  occurring  successively  at  upper  stations  so  as  to  make  them 
of  use  for  predictions  at  places  lower  down,  as  Paris  or  Mantes,  and 
to  draw  from  them  conclusions  useful  for  points  along  the  lower 
course  of  the  river.  Inspector  General  Allard,  former  President  of 
the  Commission  on  the  Forecasting  of  Floods  in  the  Ministry  of 
Public  Works,  has  given,  in  a  special  work,  a  certain  number  of  second- 
ary rules  determined  in  this  manner  (Annales  des  Fonts  et  Chaussees, 
1889,  ler  sem.,  vol.  xvii,  pp.  689  and  following). 

When  a  sufficiently  great  distance  separates  two  stations  between 
which  the  course  of  the  water  considered  does  not  receive  any  im- 
portant tributary,  or  if  the  velocity  of  propagation  of  floods  between 
these  two  points  is  small,  the  prediction  can  be  made  by  the  aid  of  a 
graphical  process  in  which  (1)  the  abscissas  are  the  maximum  stages 
occurring  at  the  upper  station  in  a  certain  number  of  previous  floods, 
(2)  the  ordinates  are  the  maxima  corresponding  to  the  lower  station. 
The  extremities  of  the  ordinates  give  generally  a  regular  curve  which 
permits  of  finding  the  highest  stage  to  be  predicted  from  the  corres- 
ponding abscissa,  the  stage  at  the  upper  station. 

An  analogous  graphic  method  was  proposed  in  1882  by  M.  Lavoinne, 
in  a  more  complicated  case,  to  study  the  relations  between  the  maxima 
of  the  Seine  at  Rouen,  that  of  the  Seine  at  Mantes,  and  the  level  of 
the  sea  at  Havre  about  thirty-six  hours  in  advance.  The  stage  at 
Havre  was  taken  as  abscissa  and  that  at  Mantes  as  ordinate,  and  along- 
side of  the  point  thus  located  was  written  the  stage  that  resulted  at 
7 


98  CHICAGO    METEOROLOGICAL   CONGRESS. 

Rouen.  If  there  was  a  constant  relation  between  these  three  variables, 
all  the  points  of  equal  stage  ought  to  be  on  a  regular  curve,  the  pro- 
jection of  a  line  of  level  on  a  surface  conceived  to  give  in  space  the 
relation  in  question.  This  proceeding,  devised  anew  by  M.  Mazoyer 
for  the  prediction  of  floods  of  the  Loire  in  the  vicinity  of  Nevers 
(Annales  des  Fonts  and  Chaussees,  1890,  2d  sem.,  vol.  xx,  pp.  451  to 
511),  is  modified  somewhat:  one  of  the  variables  is  not  always  the 
height  of  water  actually  observed  on  a  gauge  at  an  upper  station,  but 
the  mean  of  the  maximum  stages  indicated  by  the  observations  of  a 
certain  number  of  tributaries  whose  relative  influence  can  be  taken 
into  account  by  the  aid  of  proper  coefficients. 

In  the  two  cases  in  question,  the  graphical  processes  can  be  replaced 
by  tables  of  single  or  double  entry,  as  has  been  done  by  M.  Jollois  for 
the  upper  Loire.  (Annales  des  Fonts  et  Chaussees,  1881,  ler  sem.,  vol. 
I,  pp.  273  to  322.) 

It  seems  useless  to  dwell  here  on  the  investigation  of  formulas  and 
unknown  coefiicients  (by  trial  or  by  the  method  of  least  squares), 
in  fine,  on  the  graphic  representation  of  the  relation  found  in  num- 
bers by  means  of  the  processes  indicated  in  the  Nomographie  of  M. 
d'Ocagne  (Gauthier  Villars,  1892,  pp.  65  to  81).  This  latter  method 
in  particular,  is  not  yet  completely  studied,  and  its  practical  appli- 
cation in  hydrometry  can  not  be  pronounced  upon  immediately.  In 
these  investigations  the  important  point  is  to  be  satisfied  as  to  the 
conditions  indicated  for  great  floods ;  it  is  rarely  that  the  others  have 
an  equal  interest  for  dwellers  along  rivers.  j| 

Prediction  of  floods  from  rains. — At  the  present  time  it  is  possible  to 
speak  affirmatively  as  to  the  possibility  of  effectively  using  observa- 
tions of  rainfall  for  predicting  the  level  of  the  water  in  the  rivers  of 
certain  regions  ;  they  have  served  as  the  basis  for  hydrological  studies 
but  do  not  appear  to  be  easily  usable.  ( Manual  Hydrologique  du  Bassin 
de  la  Seine,  p.  50.)  ■ 

In  very  impermeable  basins  with  small  extent  of  surface  and  high 
slopes  the  details  of  observations  of  rainfall  permit  of  appreciating 
more  readily  than  elsewhere  the  probable  circumstances  of  water 
flow.  It  is  precisely  in  regions  of  this  kind  that  it  is  especiall}'-  diffi- 
cult to  procure  in  time  observations  of  the  heights  of  small  rivers 
along  the  upper  courses,  which  permit  of  eliminating  the  influence  of 
the  nature  and  configuration  of  the  ground,  its  dryness,  its  temper- 
ature, or  other  perturbing  action. 

In  studying  the  floods  of  a  very  little  river  in  the  north  of  France 
(the  Liane)  which  empties  in  the  straits  of  Calais  at  Boulogne-sur- 
Mer,  M.  Voisin  has  shown  that,  in  certain  cases  at  least,  having  re- 
gard to  these  influences,  one  can,  without  passing  through  the  inter- 
mediary of  river  gauges  at  upper  stations,  give  approximate  estimates 
of  stages  in  time  to  be  of  use.     {Annales  des  Fonts  et  Chaussees,  1888, 


FORECASTING    FLOODS.  99 

ler  sem.,  vol.  xv,  pp.  464  to  510.)  He  has  obtained  since  that  time 
certain  satisfactory  results.  Some  analogous  propositions  which 
have  not  as  yet,  however,  been  sanctioned  by  any  practical  results, 
have  been  made  by  M.  Tinbeaux  for  the  Durance.  (Annales  des  Fonts 
et  Chaussees,  1892,  ler  sem.,  vol.  iii,  pp.  166  to  196.)  Divers  studies 
of  the  same  kind  appear  to  have  been  pursued  by  the  hydrometric 
services  recently  organized  in  conformity  with  the  advice  of  the  Com- 
mission on  the  Prediction  of  Floods,  at  the  instance  of  M.  G.  Lemoine 
for  the  Ardeche,  the  Herault,  and  other  rivers  which  descend  rapidly 
from  the  Cevennes  to  the  Rhone  or  Mediterranean.  It  is  beyond 
doubt  very  difficult  to  make  numerical  forecasts  in  the  greater  num- 
ber of  cases,  but  it  is  nevertheless  a  good  deal  to  be  able  to  announce 
in  such  regions  a  few  hours  in  advance  the  approach  of  an  important 
or  dangerous  flood.  Only  two  points  so  far  seem  to  be  established  for 
the  small  drainage  area  of  the  Liane :  ( 1 )  the  possibility  of  estimat- 
ing the  degree  of  saturation  of  the  soil  in  a  certain  zone  from  the 
height  of  water  on  a  gauge  at  a  greater  or  less  distance  from  a  down- 
river station,  notably  at  the  very  place  from  which  the  predictions 
are  issued;  (2)  the  influence  of  the  hourly  rate  of  rainfall.  It  is  not 
immaterial  from  the  point  of  view  of  the  flow  of  water  that  a  certain 
depth  of  rain  had  been  caught  in  the  rain  gauges  in  a  very  short  time 
or  in  a  great  many  hours ;  in  this  latter  case  it  has  a  much  greater 
chance  of  being  absorbed  by  the  ground  or  being  in  great  part 
evaporated. 

Registering  apparatus. — All  the  information  necessary  can  be  ob- 
tained by  visual  observations  distributed  at  intervals  sufficient  for  the 
purpose  for  which  they  are  desired.  The  rapidity  of  the  phenomena, 
however,  is  at  times  so  great,  especially  in  mountainous  regions,  that 
it  is  sometimes  well  to  have,  in  addition  to  river  gauges  and  the  ordi- 
inary  rain  gauges,  apparatus  adapted  (1)  to  signal,  by  electricity,  the 
instant  of  time  when  the  quantities  to  be  observed  reach  certain  im- 
portant values,  (2)  to  register  the  details  of  their  variations. 

Different  French  makers  of  instruments  of  precision  (notably 
Messrs.  Richard,  Parenthon,  and  Chateau)  make  self-registering  river 
and  rain  gauges  of  which  the  indications  are  of  great  value.  The 
use  of  this  kind  of  apparatus  is  gradually  becoming  greater;  they 
would  be  used  to  a  much  greater  extent  were  it  not  for  the  obstacles 
of  the  very  high  price  and  the  cost  of  their  maintenance.  For  a 
stream  as  torrential  as  the  Durance  it  is  almost  indispensable  to  have 
self-registering  apparatus  at  one  station  at  least  at  the  head  waters. 

Prediction  of  floods  by  discharges. — In  order  to  satisfy  the  desire  ex- 
pressed by  the  Chairman  of  the  Section  devoted  to  Rivers  and  Floods 
of  the  Meteorological  Congress,  a  few  words  must  be  said  regarding 
the  use  of  discharge  observations  in  predicting  the  level  of  rivers. 
This  method  is  not  in  current  use  in  France  where  the  gaugings  of 


100  CHICAGO    METEOROLOGICAL   CONGRESS. 

I 

water  courses  have  only  been  made  at  a  small  number  of  places  and 
have  no  relation  to  each  other  and  are,  in  general,  only  slightly  com- ; 
parable.  To  extract  anything  from  data  of  this  kind,  one  is  especially  ■ 
embarrassed  by  the  manoeuvering  of  movable  dams  on  the  numerous ; 
rivers  where  navigation  has  been  improved  by  artificial  means.  Finally, 
there  does  not  exist  on  any  French  water  course  anything  that  can 
be  compared  to  the  great  work  done  for  the  Elbe  and  its  tributaries 
in  Bohemia  under  the  direction  of  Prof.  Harlacher  of  the  Polytechnic- 
Institute  at  Prague.  It  was  only  after  eighteen  years  of  patient  in- 
vestigation that  he  succeeded,  in  1881,  in  perfecting  his  method  of 
prediction  by  discharges,  published  over  his  signature  and  that  of 
Prof.  Richter  in  the  month  of  December,  1886  (Zeitsch  rift  far  Bauwesen, 
1887).  There  is  often  difficulty  in  choosing  two  or  three  stations 
along  head  waters,  such  that  the  sum  of  their  discharges,  increased  in 
a  certain  proportion  to  take  into  account  the  additions  from  second- 
ary streams  below,  produce  with  sufficient  exactness  the  discharge 
in  a  determinate  time  at  the  station  for  which  the  predictions 
are  to  be  made.  If  this  correspondence  is  attained,  might  not  one 
find  an  approximate  relation  by  a  simpler  application  of  the  abso- 
lute stages  or  the  rises,  without  passing  through  the  intermediary 
of  the  gaugings?  To  obtain  the  greatest  chances  of  success,  the  dis- 
charges ought  to  be  well  determined  in  connection  with  the  observa- 
tion of  levels  at  upper  points ;  there  ought  to  be  a  great  variation  of 
height  without  any  notable  change  of  volume  in  the  water  passing 
per  second;  this  supposes  that  the  valleys  are  embanked.  At  the 
same  time  an  appreciable  error  in  the  discharge  ought  not  to  involve 
at  the  lower  station  any  great  uncertainty  in  the  corresponding  height 
of  water ;  this  case  is  presented  only  in  a  flat  valley  with  a  large, 
broad  bed.  These  conditions  are  not  found  together  in  France,  where 
the  water  courses  have  for  the  most  part  a  regimen  too  variable  to 
permit  of  the  method  in  question  being  applied  advantageously. 

GENERAL    ORGANIZATION    FOR    THE    PREDICTION    OF    FLOODS    IN    FRANCE. 

Conclusion. — In  what  precedes  there  has  been  no  question  as  to  the 
dissemination  of  warnings,  for  transmission  is  not  directly  bound  up 
with  the  technical  work  of  prediction.  Scientific  progress  cannot  be 
obtained  by  decree,  admitting  that  in  many  other  cases  it  is  possibly 
realizable. 

The  important  results  obtained  by  Belgrand  for  the  basin  of  the 
Seine  preceded  all  corresponding  administrative  organization.  Yet 
the  investigations  to  which  local  services  ought  to  devote  their  ener- 
gies in  order  to  make  useful  predictions  are  often  long  and  difficult. 
The  persons  charged  with  them  give  them  special  attention  when  they 
expect  to  find  a  way  to  derive  satisfactory  rules  through  skillful  com- 
binations, and  when  the  labor  and  ingenuity  bestowed  in  such  studies 


RIVERS    OF   SIBERIA.  101 

do  not  risk  passing  unnoticed.  The  Ot)mmi8sion  on  Prediction  of 
Floods,  instituted  in  1875  under  the  Ministry  of  Public  Works  at 
Paris,  has  certainly  played  from  this  point  of  view  a  very  important 
role.  It  has  organized  in  a  permanent,  definite  manner  the  service 
of  observation,  the  preparation  of  warnings,  and  their  distribution 
throughout  almost  the  whole  of  France.  The  results  obtained  in 
France  up  to  the  present  time  have  been  attained  without  very  great 
expense,  and  without  the  powerful  means  which  have  recently  per- 
mitted the  Central  Bureau  fur  Meteorologie  unci  Hydrographie  of  the 
Grand  Duchy  of  Baden  to  produce  the  recent  magnificent  publica- 
tion on  the  Rhine  and  its  affluents.  With  more  modest  resources,  the 
hydrometric  services  of  the  different  French  basins  have  probably 
not  yet  said  the  last  word. 


5— THE  FOUR  GREAT  RIVERS  OP  SIBERIA. 
Franz  Otto  Sperk. 

The  whole  northern  portion  of  Asia  that  bears  the  name  of  Siberia, 
extending  from  the  Ural  Mountains  in  the  west  to  the  waters  of  the 
Pacific  Ocean  in  the  east,  i.  e.,  approximately  from  the  fiftieth  to  the 
one  hundred  and  fortieth  meridians  east  of  Greenwich,  covers 
(according  to  the  computation  of  Mr.  Strelbitsky)  an  area  of  231,637* 
square  miles,  or  12,757,864  square  kilometers,  not  including  the  islands. 
This  vast  territory  is  intersected  by  four  enormous  river  basins. 
Three  of  these  rivers,  the  Obi,  the  Yenisei,  and  the  Lena,  receive  their 
waters  from  the  Altai  and  Saian  mountains  and  their  numerous 
spurs,  and  empty  into  the  Arctic  Ocean ;  while  the  fourth,  the  great 
Amoor  River,  discharges  its  waters  into  the  Gulf  of  Tartary  of  the 
Pacific  Ocean.  I  shall  not  speak  of  the  rivers  of  the  extreme  north 
of  Siberia,  such  as  the  Piasina,  Khatanga,  Olenek,  Yana,  Indighirka, 
Kolyma,  Anadeer,  and  others,  although  some  of  these  are  very  large. 

The  dimensions  of  the  four  principal  river  systems  of  Siberia  are 
as  follows:  (1)  The  river  Obi  has  a  length  of  701.5  miles,  or 
5,206  kilometers;  its  basin  comprises  an  area  of  54,118  square 
miles,  or  2,980,646  square  kilometers.  (2)  The  river  Yenisei,  with 
the  Angara,  Lake  Baikal,  and  the  Upper  Angara  River,  has  a  length 
of  540.5  miles,  or  4,011  kilometers;  the  basin  extends  over  an  area 
of  37,257  square  miles,  or  2,051,996  square  kilometers.  If,  how- 
ever, the  Selenga  River  is  taken  as  the  beginning  of  the  Angara, 
both  the  length  and  the  area  of  the  basin  would  be  considerably 
increased.  (3)  The  Lena  has  a  length  of  619.7  miles,  or  4,599  kilo- 
meters;   the  area  of  its  basin  is  42,743  square  miles,  or  2,354,203 

*  The  Prussian  mile  seems  to  be  used  throughout  this  paper.  The  English  equiva- 
lent is  4.66  statute  miles.    The  temperatures  given  are  in  centigrade  degrees. — Editor. 

) 


102  CHICAGO    METEOROLOGICAL    CONGRESS. 

square  kilometers.  Finally,'*- (4)  the  Amoor  River  is  603  miles,  or 
4,478  kilometers,  long ;  and  the  portion  of  its  basin  belonging  to  the 
Russian  Empire  covers  an  area  of  18,300  square  miles,  or  1,007,901 
square  kilometers. 

There  can  be  no  doubt  as  to  the  great  importance  of  these  rivers  for 
the  climate  of  the  country.  Thus  the  annual  covering  of  these  rivers 
with  ice  and  their  delivery  from  the  ice  must  exert  a  powerful  influ- 
ence on  the  temperature  of  the  locality,  for  the  formation  of  the  ice 
absorbs  a  large  amount  of  heat,  and  the  cover  of  ice  over  the  rivers 
changes  the  conditions  of  evaporation  and  radiation  ;  again,  the  thaw- 
ing of  the  ice  appreciably  lowers  the  air  temperature  of  the  spring 
months.  Thus,  while  the  rivers  are,  so  to  speak,  a  product  of  the 
climate  of  the  country,  they  may  themselves  serve,  apart  from  direct 
meteorological  observations,  as  an  indication  of  the  greater  or  less 
amount  of  precipitation,  and  their  changes  of  level  may  allow  infer- 
ences as  to  the  annual  distribution  of  the  precipitation.  The  exist- 
ence of  the  mighty  rivers  of  Siberia,  with  their  numerous  powerful 
and  extensive  tributaries,  shows  clearly  that  Siberia  is  not  deficient 
in  precipitation ;  and  the  considerable  changes  of  level  taking  place 
in  these  innumerable  rivers  at  different  times  indicate  that  this  rather 
large  amount  of  precipitation  is  not  uniformly  distributed  over  the 
various  parts  of  Siberia  and  through  the  seasons.  In  general,  pre- 
cipitation is  greater  in  the  west  in  summer,  in  the  east  in  winter. 
Unfortunately,  the  questions  that  meteorology  might  raise  concerning 
the  Siberian  rivers  have,  as  yet,  hardly  lieen  seriously  considered. 
Besides  the  work  of  Dr.  Rykatschew  "  On  the  Opening  and  Freezing 
of  Rivers,"  and  that  of  Dr.  Stt^Hing  "On  the  Discharge  of  Water  of 
the  Angara,"  some  scanty  material,  not  yet  scientificall}^  elaborated, 
is  to  be  found  in  various  works  concerning  thg  discharge  of  rivers  and 
allied  problems. 

The  present  brief  sketch  is  based  on  all  the  material  I  have  been 
able  to  collect,  and  on  my  personal  observations  and  recollections 
from  an  eighteen  years'  residence  in  Siberia. 

I  shall  begin  with  the  freezing  and  opening  of  the  rivers,  these 
phenomena  accompanying  the  transition  from  summer  to  winter,  and 
again  from  the  cold  to  the  warm  season.  While  the  times  of  the 
freezing  and  opening  of  the  rivers  vary  within  rather  wide  limits, 
these  limits  are  more  narrow  in  Siberia  than  in  European  Russia. 
I  give  below  a  table  derived  from  the  results  of  Dr.  Rykatschew,  and 
exhibiting  the  mean  and  maximum  deviations  from  the  general  means 
for  the  separate  periods  : 


RIVERS    OF    SIBERIA. 

Table  sJiowing  mean  and  maximum  deviations. 


103 


For  a  20-year  period. 

Opening. 

Freezing. 

Free  from  ice. 

Mean. 

JVIaximum. 

Mean. 

Maximum. 

Mean. 

Maximum. 

o 

±  i-i 
±  i.c 

0 
—  3 

0 
±2.1 
±  1.6 
±2.3 

0 

±4 

±3 

6 

0 
±2.1 
±  2.6 
±3-3 

0 

±  4 

River  Yenisei  at  Yeniseisk 

8 

For  a  30-year  period. 

Opening. 

Freezing. 

Free  from  ice. 

Mean. 

Maximum. 

Mean. 

Maximum. 

Mean. 

Maximum. 

0 
±  0.8 
±0.5 
±1-4 

0 
2 

±  I 

±3 

0 
±1-7 

0 
+  4 

0 

±2.1 
(1) 

±  1-5 

0 
+  4 

River  Yenisei  at  Yeniseisk 

River  Angara  at  Irkutsk 

5 

1  No  information. 

Investigation  has  shown  generally  that  in  the  more  central,  and 
consequently  more  continental,  portions  of  a  country  the  times  of 
freezing  and  opening  of  the  rivers  are  subject  to  smaller  annual 
variations.  I  give  on  p.  116  a  table,  taken  from  the  work  of  Dr. 
Rykatschew,  which  shows  the  times  at  which  the  princii)al  Siberian 
rivers  begin  and  cease  to  be  covered  with  ice.  In  this  connection  it 
must  be  observed  that  the  following  more  extended  series  of  observa- 
tions are  available :  A  series  of  one  hundred  years  only  for  the  river 
Angara ;  a  series  of  eighty  years  for  the  Obi  at  Barnaul,  and  for  the 
opening  of  the  Yenisei  at  Yeniseisk.  The  observations  for  most  of  the 
other  rivers  extend  over  small  periods  of  time.  As  the  phenomena 
of  the  freezing  and  opening  of  the  rivers  are  closely  connected  with 
the  time  of  first  occurrence,  as  well  as  with  the  duration  of  air  tem- 
peratures below  zero  in  the  fall  and  of  temperatures  above  the  freez- 
ing point  in  the  spring,  I  have  also  given  in  the  table  the  following 
mean  results :  ( 1 )  The  time  of  the  first  occurrence  of  a  mean  temper- 
ature of  zero  (for  twenty-four  hours) ;  (2)  the  interval  from  the  first 
day  of  zero  temperature  to  the  day  of  opening  and  freezing,  respec- 
tively;  (3)  the  number  of  days  between  the  mean  zero  temperature 
of  the  spring  and  the  fall.  It  would  also  be  of  interest  to  have  data 
concerning  the  sum  of  temperatures  below  zero  required  for  the  freez- 
ing of  the  rivers,  but  we  have  such  data  only  for  the  Angara,  for 
which  Dr.  Woeikof  derives  the  figure  99.8°,  while  for  the  Neva  only 
42°  are  required. 

It  appears  from  Mr.  Rykatschew's  maps,  illustrating  the  simulta- 
neous opening  and  freezing  of  the  rivers,  that  the  earliest  opening  of 


104  CHICAGO    METEOROLOGICAL    CONGRESS. 

Siberian  rivers  begins  about  the  2l8t  of  April  in  the  southern  portion 
of  west  Siberia,  between  the  cities  of  Semipalatinsk  and  Barnaul, 
From  there  it  moves  to  the  upper  part  of  the  Yenisei,  beginning  later 
toward  the  east,  or,  if  simultaneous,  farther  south.  About  the  Ist 
of  May  the  opening  of  the  rivers  already  extends  to  the  middle  of  the 
course  of  the  Amoor.  On  the  21st  of  May  the  opening,  beginning  in  the 
west  near  Berezov,  extends  eastward,  bends  at  Yakutsk  somewhat  to 
the  south,  and  turns  on  the  shores  of  the  Okhotsk  Sea  abruptly  south- 
west towards  Nikolaifsk  on  the  Amoor.  The  Yenisei,  in  the  lower 
part  of  its  course,  between  Toorookhansk  and  the  mouth  of  the  river, 
throws  off  its  covering  of  ice  only  at  the  beginning  of  June ;  the  same 
is  true  of  the  rivers  Yana  and  Kolyma  in  their  lower  course.  Toward 
the  end  of  June  the  mouth  of  the  Lena  becomes  open,  and  partly  that 
of  the  Yenisei.  But  even  in  the  month  of  July  some  smaller  rivers 
can  be  found  covered  with  ice  on  the  Taimyr  Peninsula.  According 
to  the  means  deduced  from  the  ol^servations,  the  opening  of  the 
more  important  Siberian  rivers  takes  place  sixteen  days  after  the 
occurrence  of  a  mean  temperature  of  the  air  of  zero ;  for  the  smaller 
rivers  the  interval  is  twelve  days. 

The  gradual  onward  motion  ,of  the  boundary  of  the  ice  covering 
from  the  south  to  the  north  goes  on  more  rapidly  in  the  east.  In 
eastern  Siberia,  in  N.  50°,  it  takes  place  in  a  month,  the  motion 
northward  being  at  the  rate  of  10°  in  nineteen  days,  but  on  one  and 
the  same  parallel  the  opening  is  considerably  retarded  toward  the 
east  in  the  more  southern  parts  of  the  country  in  comparison  with 
the  northern  parts,  and  it  is  evidently  connected  with  the  direction 
of  the  isothermal  lines  and  depends  on  local  topographical  conditions. 

The  covering  of  the  rivers  with  ice,  /.  e.,  the  process  of  the  forma- 
tion of  the  ice  on  the  rivers,  is  very  interesting  in  Siberia,  but, 
unfortunately,  it  has  been  investigated  very  little.  It  is  known  from 
the  investigations  of  Messrs.  Shchukin  and  Schwarz  that  the  forma- 
tion of  ice  in  the  Angara,  and  also  in  some  other  rivers,  for  instance 
in  the  Olokma,  takes  place  not  only  on  the  surface  but  at  the  bottom 
as  well. 

Special  mention  should  here  be  made  of  the  Angara,  as  this  river 
is  distinguished  from  other  Siberian  rivers  by  several  peculiarities. 
Forcing  its  way  through  the  rocky  shores  of  Lake  Baikal,  the  Angara 
carries  its  waters,  cold  and  clear  as  crystal,  in  rapid  flow  from  the 
lake  to  the  city  of  Irkutsk ;  and  on  this  distance  of  only  about  70 
kilometers  its  bed  has  a  fall  of  80  meters,  in  other  words,  it  has  an 
average  grade  of  0.43  meters  per  kilometer.  Along  this  whole  dis- 
tance the  Angara  does  not  receive  a  single  important  tributary,  and 
represents  a  pure  type  of  a  lake  river.  From  this  it  might  be  ex- 
pected that  its  level  would  vary  but  slightly.  It  appears,  however, 
as  we  shall  see  later,  that  the  height  of  its  water  level  is  subject  to 


RIVERS    OF    SIBERIA.  106 

very  considerable  and  abrupt  variations.  Another  peculiarity  of  the 
Angara  is  its  late  freezing,  which  takes  place  about  eighty  days  after 
the  beginning  of  frosts,  at  a  time  when  the  cold  reaches  not  less  than 
— 25° ;  it  occurs  more  than  a  month  and  a  half  later  than  in  other 
Siberian  rivers  situated  in  the  same  latitude.  A  third  peculiarity  of 
the  Angara  lies  in  the  fact  that  its  overflow  takes  place  not  in  spring, 
summer,  or  fall,  as  is  the  case  with  other  rivers,  but  in  winter,  at  a 
time  of  the  severests  frosts,  when  the  river  is  freezing.  Dr.  Stelling 
believes  that  the  overflow  of  the  Angara  at  the  time  of  its  freezing  is 
due  partly  to  the  diminution  of  the  velocity  of  the  current  arising 
from  the  friction  of  the  water  on  the  ice  crust,  and  partly  to  the  nar- 
rowing of  its  bed  through  the  ice.  The  latter  cause  is  probably  the 
principal  one.  It  is  to  be  regretted  that  no  exact  data  are  available 
as  to  the  distance  over  which  the  Angara  below  Irkutsk  is  covered 
with  ice  at  an  earlier  period  than  at  this  city.  The  obstruction  by 
ice  in  these  portions  of  river,  which  freeze  at  an  earlier  time,  are  the 
main  cause  of  the  overflows. 

I  shall  now  give  a  brief  extract  from  Dr.  Schwarz's  observations  on 
the  freezing  of  the  Angara  at  Irkutsk  in  the  ^vinter  of  1856-1857 : 
On  December  14  ice  began  forming  along  the  banks;  on  the  18th, 
when  the  temperature  of  the  air  fell  to  — 30.7°,  while  that  of  the 
water  was  -|-0.03,  the  whole  river  began  to  be  covered  with  ice  floes, 
and  the  ice  on  the  banks  extended  to  a  considerable  distance  into  the 
river.  At  the  bottom  of  the  river  could  be  noticed  numerous  ice 
crystals  which  would,  from  time  to  time,  break  loose  from  the  bottom 
and  rise  to  the  surface.  On  December  19,  the  temperature  of  the  air 
being  — 35°,  the  ice  crystals  at  the  bottom  disappeared,  and  the  river 
continued  to  carry  ice  floes.  Beginning  with  January  15,  1857,  the 
water  began  to  rise  in  the  river,  the  temperature  of  the  air  being 
— 11.7°.  On  the  18th  the  river  overflowed  all  the  low  bank  near  the 
city ;  on  the  19th  the  water  rose  to  a  height  of  3  meters,  and  on  the 
same  day,  the  temperature  being  — 24.1°,  the  main  channel  of  the 
Angara  became  completely  covered  with  an  ice  sheet.  Nevertheless, 
the  overflow  of  the  river  continued  to  increase  up  to  January  24,  and 
only  on  the  25th  the  water  began  to  fall.  It  must  also  be  noticed 
that  the  fall  of  the  water,  after  the  overflow  has  reached  its  greatest 
height,  takes  place  very  gradually,  the  water  continuing  to  fall  for  a 
month.  Thus  it  appears  from  the  observations  on  the  freezing  of 
the  Angara  that  ice  crystals  form  at  the  bottom,  that  this  goes  on, 
with  interruptions,  in  spite  of  the  increasing  cold,  and  that  these 
crystals  rise  to  the  surface  in  the  form  of  laminas  which  freeze  on  to 
the  ice  forming  on  the  surface. 

I  add  the  following  details  as  to  the  time  of  freezing  of  the  Angara : 
In  the  year  1739  the  river  became  completely  covered  with  ice  on 
January  9,  simultaneously  with  Lake  Baikal.     This  is  a  rare  occur- 


106  CHICAGO    METEOROLOGICAL   CONGRESS. 

rence,  as  the  Baikal  usually  freezes  earlier.  In  1751  there  was  a  very 
heavy  inundation  at  the  time  of  freezing,  January  8.  In  the  winter 
of  the  year  1755  the  river  began  being  covered  with  ice  only  on  Feb- 
ruary 2 ;  the  ice,  however,  was  carried  away  seven  times,  and  there 
was  hardly  any  period  of  complete  covering  with  ice.  In  the  year 
1870,  when  the  river  became  covered  with  ice  on  January  15,  a  large 
part  of  the  city  of  Irkutsk  and  many  settlements  along  the  Angara 
were  inundated.  The  same  thing  occurred  in  1887,  when  the  river 
froze  on  January  18  ajid  19,  and  the  overflowing  waters  carried  large 
masses  of  ice  with  them.  It  is  also  worthy  of  notice  that,  from  the 
very  beginning  of  frost,  i.  e.,  from  the  month  of  October,  a  heavy  fog 
was  constantly  hovering  over  the  Angara  River.  This  fog  disappeared 
only  when  the  river  became  covered  with  ice. 

Returning  again  to  the  results  obtained  by  Dr.  Rykatschew,  we  find 
that  the  covering  of  the  rivers  with  ice  is  subject  to  greater  variations 
than  the  opening,  and  that  it  proceeds  in  the  opposite  order,  i.  e.,  from 
the  northeast  to  the  southwest.  First  of  all  become  covered  with  ice 
the  small  rivers  of  the  Taimyr  Peninsula,  as  early  as  in  September. 
Next,  about  two  weekf  later,  such  rather  considerable  rivers  as  the 
Piasina,  Indighirka,  Yana,  emptying  into  the  Arctic  Ocean,  begin  to 
freeze  almost  simultaneously,  and  the  boundary  of  the  ice  covering 
advances  pretty  rapidly,  forming  two  bends  toward  the  south  and 
southwest,  one  in  eastern  Siberia  along  the  Amoor  the  other  in  west 
Siberia  toward  the  upper  course  of  the  rivers  Tom  and  Omi ;  an  up- 
ward bend  occurs  along  the  valley  of  the  Yenisei. 

The  formation  of  these  bends  in  the  progress  of  the  ice  sheet  on  the 
rivers  depends  both  on  the  distribution  of  the  air  temperatures  and 
on  the  slow  cooling  of  the  large  mass  of  water  in  the  rivers.  To  the 
same  cause  is  due  the  late  freezing  of  the  northern  parts  of  the  other 
large  rivers,  viz.,  the  Obi  and  the  Lena,  In  its  progress  from  east  to 
west  the  covering  of  the  rivers  with  ice  is  retarded  about  ten  days  for 
every  24°  of  longitude,  while  the  southward  march  of  the  boundar}- 
of  the  ice  sheet,  from  the  polar  circle  to  the  fiftieth  parallel,  is  ac- 
complished, on  an  average,  in  thirty-one  days. 

As  regards  the  duration  of  the  ice  covering,  it  varies  between  very 
wide  limits.  Thus,  at  the  mouth  of  the  Piasina  the  ice  stays  three 
hundred  days,  while  in  southern  Siberia  the  duration  is  not  over  one 
hundred  and  sixty  days.  An  exception  is  made  by  the  Angara,  which, 
after  leaving  the  Baikal,  for  a  distance  of  7  kilometers,  never  freezes 
at  all,  owing  to  the  rapidity  of  its  current,  and  this  in  spite  of  tem- 
peratures of  — 40°,  and  of  the  fact  that  for  a  period  of  one  hundred  and 
seventy  days  the  temperature  always  remains  below  zero.  The  same 
phenomenon  occurs  in  the  course  of  the  Yenisei,  in  the  narrow  rocky 
passes  of  the  Saian  Mountains,  and  in  a  large  number  of  small  moun- 
tain rivers,  which  in  some  parts  do  not  freeze  at  all,  owing  either  to 


RIVERS   OF    SIBERIA.  107 

the  velocity  of  the  current  or  to  springs  of  warmer  water  emptying 
into  their  beds. 

In  the  large  rivers  the  ice  stays,  on  an  average,  nine  days  longer 
than  the  duration  of  the  normal  temperature  of  zero ;  in  the  small 
rivers,  only  five  days  longer.  The  freezing  of  the  large  rivers  takes 
place  twenty-four  days  after  the  occurrence  of  a  mean  temperature 
of  the  air  of  zero ;  the  freezing  of  the  small  rivers  occurs  seventeen 
days  after  this  temperature.  The  extremes  of  temperature  between 
which  the  freezing  times  oscillate  are  greater  than  those  for  the  open- 
ing of  the  rivers,  but  far  more  constatit.  Thus  the  intervals  between 
the  earliest  and  latest  openings  and  freezings  are : 

For  the—  Openings.    Freezings. 

Obi  at  Barnaul  

Yenisei  at  Yeniseislc 

Angara  at  Irltutsk 

Lena  at  Kirensk 

Lena  at  Yakutsk 

From  the  information  gathered  by  the  Polar  Expedition  of  1882- 
1884  it  may  be  assumed  that  the  opening  of  the  mouth  of  the  Lena, 
in  N.  70°  23',  E.  126°  35',  occurs  on  May  25,  and  the  covering  of  the 
river  with  ice  on  October  2,  so  that  the  river  is  only  ninety-nine  days 
free  from  ice.  The  mean  value  of  the  interval  between  the  times  of 
extreme  openings  is  a  little  over  a  month  for  the  rivers  of  Siberia, 
and  the  mean  interval  between  the  extreme  freezings  does  not  exceed 
thirty-five  days,  while  for  the  rivers  of  Russia  the  latter  interval 
amounts  to  fifty-two  days.  The  constancy  of  the  openings  and  freez- 
ings is  particularly  remarkable  in  the  case  of  the  Lena,  as  this  river 
flows  through  a  region  having  an  extremely  continental  climate. 
Thus,  the  mean  duration  of  the  ice  covering  of  the  Lena,  near 
Kirensk,  is  two  hundred  and  three  days ;  and  in  the  course  of  the 
forty-two  years  for  which  there  are  observations,  it  happened  only 
twice  that  the  ice  stayed  fourteen  days  less,  and  only  once  that  it 
stayed  thirteen  days  longer  than  the  normal  duration. 

As  regards  the  thickness  of  the  ice  covering  the  rivers,  the  informa- 
tion is  exceedingly  scanty.  We  happen  to  know  that  in  the  lower 
course  of  the  Yenisei  the  thickness  of  the  ice  in  severe  winters  will 
reach  2.5  meters ;  and  that  on  the  Angara,  at  Irkutsk,  on  March  9, 
1887,  the  greatest  thickness  was  1.14  meters,  on  the  Baikal  from  1.2 
to  1.8  meters. 

Concerning  the  variations  of  level  in  the  rivers,  we  have  the  scien- 
tifically conducted  observations  of  Dr.  Stelling  for  the  Angara,  but 
only  for  1886-1887.  It  appears  from  these  observations  that  the 
water  level  of  the  Angara  is  subject  to  considerable  variations  in  the 
course  of  the  year,  and  that  the  annual  curve  differs  decidedly  from 


108  CHICAGO    METEOROLOGICAL    CONGRESS. 

those  for  the  rivers  of  European  Russia  and  of  west  Siberia.  Thus, 
in  1887,  the  mean  level  of  the  Angara  at  Irkutsk  (in  meters)  was  as 
follows : 

January,  4.35;  February,  3.78;  March,  4.57;  April,  6.19;  May, 
6.08;  June,  5.84;  July,  5.35;  August,  5.14;  September,  4.92 ;  October, 
5.06 ;  November,  5.44 ;  December,  5.82. 

These  figures  indicate  by  how  many  meters  the  water  level  of  the 
Angara  was  below  the  mark  established  at  the  entrance  to  the 
Museum ;  they  are  daily  means  from  three-hour  observations  taken 
7  a.  m.,  1  p.  m.,  and  7  p.  m.  * 

The  daily  observations  showed  that,  beginning  with  the  principal 
maximum  which  occurs  toward  the  end  of  January,  the  water  level 
of  the  river  falls  pretty  uniformly  to  the  second  half  of  March ; 
then,  at  the  opening  of  the  river,  which  takes  place  very  rapidly  and 
without  overflow,  a  still  greater  fall  occurs ;  but  from  the  beginning 
of  April  to  the  beginning  of  June  the  water  rises  slowly.  In  July 
the  rise  becomes  more  pronounced,  and  in  September  the  level 
reaches  a  second  smaller  maximum,  arising  from  the  great  amount 
of  precipitation  in  the  Baikal  region.  At  the  expiration  of  the  rainy 
period  the  water  level  of  the  Angara  begins  to  fall  slightly,  continuing 
to  do  so  with  slight  oscillations  until  the  period  of  freezing.  It  thus 
appears  that  in  spring,  /.  ?.,  at  the  time  of  the  greatest  overflows  of 
the  rivers  of  Russia  and  west  Siberia,  the  height  of  the  water  in  the 
Angara  is  usually  least.  This  is  largely  due  to  the  small  amount  of 
snow  in  the  Trans-Baikal  and  on  the  mountains  near  Lake  Baikal, 
which  supply  the  affluents  of  this  lake  with  water;  also  to  the  sloiv 
thaiving  of  the  snow  during  the  cold  and  dry  spring,  and  to  the  heavy 
icinds  which  produce  intensified  evaporation  accompanied  by  dryness 
of  the  air.  On  the  other  hand,  during  the  latter  part  of  the  summer 
and  the  beginning  of  fall,  when  in  Russia  everybjdy  complains  of  a 
lack  of  water,  the  Trans-Baikal  country  is  visited  by  frequent  rains. 
This  abundance  of  precipitation  is  due  to  the  monsoon  which,  in 
some  years,  extends  into  a  portion  of  the  Province  (Gubernia)  of 
Irkutsk.  All  the  rivers  then  begin  to  rise,  not  excepting  even  the 
Selenga,  if  we  may  judge  from  the  scanty  information  obtainable  for 
this  river.  Even  the  level  of  Lake  Baikal,  in  spite  of  the  enormous 
extent  of  its  surface  will,  in  some  years,  rise  appreciably. 

Of  the  changes  of  level  of  other  Siberian  rivers,  and  of  the  times  of 
greatest  height  of  the  water,  we  can  judge  only  from  the  available 
data  as  to  overflows  and  inundations  caused  by  such  overflows.  Thus, 
beginning  in  west  Siberia,  in  the  basin  of  the  Obi,  the  overflows  of 
the  rivers  are  usually  observed  in  the  spring.  What  contributes  most 
to  the  intensity  of  the  overflow  is  the  early  opening  of  the  rivers,  the 
great  amount  of  the  snowfall  in  winter,  in  particular  if  the  snow  falls 
on  a  previously  frozen  soil,  the  rapid  approach  of  warm  weather,  or, 


RIVERS   OF    SIBERIA. 


109 


what  is  called,  a  "kind  spring,"  which  causes  the  simultaneous  open- 
ing of  many  rivers.  In  the  east,  on  the  other  hand,  owing  to  the  long 
and  uninterrupted  prevalence  of  the  anticyclone  in  winter  time,  the 
winters  are  marked  by  an  exceedingly  small  amount  of  snowfall, 
while  in  summer,  during  the  reign  of  the  summer  monsoon  which 
carries  moisture  from  the  Pacific  Ocean,  there  is  abundant  rainfall, 
causing  heavy  overflows  of  the  rivers,  especially  in  the  Amoor  country. 
It  is,  however,  not  yet  decided  how  far  the  rains  caused  by  winds 
from  the  Pacific  extend  into  the  interior  of  eastern  Siberia.  But  the 
heavy  inundations  occurring  sometimes  in  the  Province  of  Irkutsk  in 
summer  would  seem  to  indicate  that  the  influence  of  the  monsoon 
occasionally  reaches  this  territory. 

To  characterize  the  distribution  of  the  precipitation  over  Siberia, 
I  give  the  following  results  derived  by  Dr.  Woeikof  for  the  mean 
precipitation  as  percentage  of  the  total  annual  amount : 


Place. 


>> 

>i 

c 

s 

.a 

0! 
S 

a 

OS 

a 

X> 

.a 
0 

03 

u 
p. 

< 

c 
a 

"-5 

a 
< 

fa 

0. 
n 

32 

2 

0 

0 

s 

> 
0 

5 

3, 

?■ 

6 

7 

13 

17 

g 

12 

II 

3 

2 

3 

4 

II 

14 

17 

18 

9 

« 

4 

4 

3 

5 

6 

14 

17 

13 

12 

8 

I 

O.q 

o.q 

0-5 

5 

23 

29 

25 

9 

2 

1.8 

0-5 

0.4 

l-.S 

3 

6 

16 

26 

28 

12 

3 

1.8 

3 

3 

4 

6 

8 

10 

10 

18 

21 

8 

Semipalatinsk 

Barnaul 

Irkutsk 

Kiakhta 

Nerchinsk 

Nicolaifsk  on  the  Amoor 


It  appears  from  these  data  that  the  amount  of  precipitation  is  dis- 
tributed over  the  year  more  uniformly  in  western  Siberia  than  in 
eastern  Siberia.  The  lack  of  uniformity  is  particularly  striking  in 
the  Trans-Baikal  country. 

For  the  Province  of  Irkutsk  we  have  observations  for  a  considera- 
ble period  at  the  city  of  Irkutsk ;  these  give  for  the  annual  distribu- 
tion of  the  precipitation  (in  millimeters)  the  following  figures:  Jan- 
uary, 19.2;  February,  13.2;  March,  10.0;  April,  14.1;  May,  26.5; 
June,  62.1;  July,  72.1;  August,  63.6;  September,  41.6;  October,  19.3; 
November,  15.8 ;  December,  22.5. 

But  from  year  to  year  the  monthly  amount  of  moisture  varies  very 
much.  Thus,  in  June  the  greatest  mean  precipitation  was  161.6  mm. 
(in  1877);  in  July,  131.5  mm.  (in  1878);  in  August,  107.8  mm.  (in 
1884),  while  in  winter  the  maximum  precipitation  reached  only  48.3 
mm.  in  January,  1882.  But  there  are  years  in  which  the  precipita- 
tion for  January  and  February  is  equal  to  zero. 

The  mean  amount  of  precipitation  at  Irkutsk  is  as  follows :  Winter, 
54.9  mm.;  spring,  50.6  mm.;  summer,  197.8  mm.;  autumn,  88.1 
mm.;  in  the  driest  summer  there  was  78.4  mm.  (1888),  and  in  the 
wettest  304.6  mm.  (1883).  Besides,  the  amount*of  precipitation  in 
any  given  year  is  distributed  very  differently  over  the  territory  of 


no 


CHICAGO    METEOROLOGICAL    CONGRESS. 


the  Province  of  Irkutsk,  as  will  appear  from  the  following  table 
for  1887 : 


Place. 


ter. 

Spring. 

Summer. 

26.1 
32-2 

42.2 

68.2 

89.2 
119-7 

41.0 
18.6 

42.6 
30-7 

81.8 
282.0 

25.0 
15-1 

62.8 
52-4 

163.7 
252.1 

6-3 

25-7 

225.9 

Autumn. 


North— 

Bashchikovo  ., 
Usti-Kuta 

West— 

Birinsa 

Cheremkhovo  . 

East- 
Irkutsk  

Shimki , 

Southeast — 

Tunka  (1889) .. 


141-4 
109.3 

96.6 
76.0 

54.7 
40.7 

66.3 


In  the  Amoor  territory  the  want  of  uniformity  in  the  distribution  of 
the  precipitation  in  the  course  of  the  year  is  still  greater.  Thus  in 
1878  the  amount  in  millimeters  was  as  follows : 


Place. 


Nerchinsk  Mining  Works 

Blagovechensk  

Khabarovka 

Nikolaifsk 

Vladivostok 

Uga  Harbor  ( 18&0) 


Winter. 

Spring. 

Summer. 

4-7 

24.0 

233-4 

0.0 

83.1 

204.6 

3-9 

71.9 

220.0 

67-5 

77-3 

177.1 

7-6 

46.1 

100.7 

29-3 

198.5 

270.4 

Autumn. 


103.4 
48.2 
74.2 

155- 1 
90-3 

348.8 


To  illustrate  the  non-uniformity  of  the  distribution  of  precipitation 
during  the  summer  months  in  different  years,  I  give  the  following 
two  years : 


Place. 


Nerchinsk 

Blagovechensk 
Khabarovka... 


1878. 


June. 


49-3 
36.6 
31.9 


August. 


98.7 
71-7 
49-4 


1880. 


June. 


149. 1 
56.0 
II4-5 


August. 


159.8 
119.5 

184.0 


The  abundance  of  moisture  in  the  Amoor  territory,  accompanied  at 
the  same  time  by  cloudy  weather,  low  temperature,  and  reduced  evapo- 
ration, is  the  cause  of  heavy  inundations  in  summer.  Although  the 
ratio  of  the  amount  of  precipitation  in  the  wettest  to  that  in  the  dri- 
est summer  month  is  considerably  less  at  Irkutsk  than  in  the  Trans- 
Baikal,  yet  it  is  much  greater  than  at  Yeniseisk  and  other  localities 
situated  farther  west  and  agreeing  more  closely  in  this  respect  with 
Russia. 

I  now  proceed  to  give  a  brief  account  of  the  data  concerning  inun- 
dations available  for  Siberia.  I  begin  in  the  west.  An  unusually 
large  inundation  took  place  in  the  spring  of  the  year  of  1857  along 
the  western  affluents  of  the  Obi.  It  began  on  the  river  Vagal  and 
its  tributaries.  In'  the  same  spring  an  unusual  increase  of  water  was 
also  noticed  in  the  rivers  Irtish,  Tobol,  Toora,  Omi,  and  others.     Thus, 


RIVERS    OF    SIBERIA.  Ill 

on  May  20,  the  river  Irtish  overflowed  its  banks  near  Tobolsk ;  on 
June  1  the  water  had  there  risen  to  a  height  of  6  meters  above  its 
mean  level,  flooding  four  hundred  houses.  The  waters  began  falling 
on  June  10.  The  highest  rise  of  the  water  in  the  Irtish,  near  the  city 
of  Omsk,  was  only  2  meters  above  the  mean  level.  In  the  river  Toora 
the  water  often  rises  to  a  considerable  height  at  the  time  of  the  spring 
floods,  which  wull  continue  from  thirty  to  seventy-five  days.  At  the 
greatest  of  these  floods,  in  1854,  1857,  and  1870,  the  waters  of  the 
Toora  rose  from  6.5  to  9  meters  above  its  ordinary  level  near  the 
cities  of  Toorinsk  and  Tioomen.  The  greatest  inundation  of  the 
river  Tom,  near  Tomsk,  is  said  to  have  taken  place  in  the  year  1804, 
when  the  ice  in  the  river  began  to  move  on  May  11,  and  on  the  12th 
the  overflow  had  reached  such  dimensions  as  to  inundate  five  districts 
in  the  lower  portion  of  the  town.  On  May  13  and  14  the  water  rose 
still  0.75  meters  higher,  carrying  ice.  Altogether,  the  water  rose  5 
meters  above  the  ordinary  level.  Beginning  with  May  15,  the  water 
fell  rapidly.  Next  to  this  the  heaviest  inundation  of  the  Tom 
occurred  in  1843,  from  April  20  to  26,  and  in  1887,  from  April  25 
to  27. 

When  the  ice  opens  on  the  Yenisei  River  the  city  of  Krasnoyarsk 
generally  suffers  less  from  the  floods  than  the  city  of  Yeniseisk,  which 
is  situated  farther  down  on  the  river.  At  Yeniseisk  the  overflows  are 
particularly  heavy  when  the  ice  opens  at  the  same  time  in  the  Yenisei 
and  in  the  Upper  Toongooska  (Angara)  and  Tasieieva.  Usually,  how- 
over,  the  ice  opens  six  days  later  on  the  former  and  twelve  days  later 
on  the  latter  than  on  the  Yenisei.  In  the  course  of  the  last  sixty  years 
there  were  in  all  eleven  inundations,  of  which  those  in  the  years  1800 
and  1857  were  the  most  destructive.  The  Yenisei  overflows  twice  a 
year.  One  overflow  usually  occurs  in  spring,  in  the  latter  part  of  May, 
and  is  called  the  "  snow  water."  In  some  years  the  water,  at  the  time 
of  the  spring  overflow,  will  reach  a  height  of  14  meters  above  the 
mean  level.  The  other  overflow,  which  is  less  important  and  is  called 
"root  water,"  occurs  generally  toward  the  end  of  June;  it  is  due  to 
the  snow  melting  in  the  mountains. 

In  1870  a  heavy  summer  inundation  occurred  in  the  Nizhnee-Oodinsk 
district  of  the  Provinc.e  of  Irkutsk,  in  the  basin  of  the  rivers  Ooda 
and  Ya,  which  are  affluents  of  the  Angara.  The  former  overflowed 
its  banks  on  July  5  and  inundated  almost  the  whole  valley  through 
which  it  flows,  the  water  rising  particularly  in  narrow  places  hemmed 
in  by  rocks.  The  city  of  Nizhnee-Oodinsk  was  the  principal  sufferer ; 
in  the  various  villages  situated  along  the  valley  of  the  Ooda,  ninety- 
nine  houses,  two  mills,  and  a  sentinel's  box  were  destroyed  and  carried 
away ;  two  men  and  a  great  number  of  cattle  were  killed.  In  the 
river  Ya  and  in  its  right-hand  tributary,  Aza,  the  water  began  rising 
on  July  4,  and  on  the  9th  the  waters  rushed  over  the  banks  with  such 


112  CHICAGO    METEOROLOGICAL   CONGRESS. 

rapidity  and  such  incredible  power  that  an  "oboz"  (row  of  wagons 
for  transportation)  laden  with  tea,  standing  near  the  bank,  did  not 
have  time  to  escape  and  was  carried  away  by  the  flood.  On  July  8  a 
heavy  overflow  began  also  in  the  valley  of  the  Biriusa,  an  affluent  of 
the  Ooda. 

The  Angara,  as  mentioned  above,  has  its  overflow  near  Irkutsk  in 
winter.  This  winter  high  water  is  an  annual  phenomenon,  though 
varying  in  intensity  more  or  less  from  year  to  j^ear.  There  are  no 
exact  data  as  to  how  far  down  the  river  this  winter  overflow  extends. 
It  is  known,  however,  that  at  the  village  Bratsky-Ostrog,  situated  on 
the  Angara,  310  kilometers  below  Irkutsk,  the  river  overflows  at  the 
time  of  the  breaking  up  of  its  ice  in  the  spring,  and  inundates  the 
settlements  situated  on  its  banks. 

The  difference  between  the  summer  and  winter  water  level  of  Lake 
Baikal  does  not  generally  exceed  1  meter,  though  sometimes  it 
amounts  to  as  much  as  3  meters.  During  the  very  rainy  sum- 
mer of  the  year  1869  the  waters  of  Lake  Baikal  rose  4.5  meters  above 
the  usual  level.  Considering  the  great  dimensions  of  this  lake  (about 
34,180  square  kilometers),  this  enormous  increase  of  water  gives  an 
indication  of  the  immense  quantities  of  water  which  the  Baikal 
must  receive  from  the  rivers  emptying  into  it.  According  to  the  Ir- 
kutsk records,  there  were  in  that  summer  twenty-four  cloudy  days  in 
July  and  twenty-one  in  August.  Now,  on  an  average,  there  cor- 
responds to  every  rainy  day  the  following  amount  of  precipitation  : 
In  June,  2.83  millimeters  (maximum,  17.4);  in  July,  5.87  (maxi- 
mum, 27.6) ;  in  August,  6.49  (maximum,  64.6) ;  and  in  September, 
0.84  (maximum,  7.4).  It  follows  that  the  rise  of  the  water  level  of 
the  Baikal  was  directly  dependent  upon  the  great  amount  of  precipi- 
tation received  in  the  surrounding  country  at  the  time  of  the  sum- 
mer monsoon ;  this  precipitation  being  carried  into  the  Baikal  by 
the  numerous  rivers  emptying  into  it,  of  which  there  are  as  many  as 
three  hundred  and  thirty-six.  Among  these  affluents  there  are  three 
of  considerable  size,  viz.,  the  Selenga,  the  Upper  Angara,  and  the  Bar- 
goozeen.  The  only  outflow  for  the  waters  of  the  Baikal  is  furnished 
by  the  Angara.  The  area  from  which  the  affluents  of  Lake  Baikal 
collect  their  waters  has  been  computed  as  320,500  square  kilometers. 

The  river  Lena,  in  its  upper  course,  does  not  overflow  when  the  ice 
breaks ;  a  small  increase  of  its  water  level  occurs  in  the  second  half 
of  May,  when  the  snow  melts  in  the  mountains.  The  time  of  great- 
est increase  of  water  is  usually  in  the  middle  of  July ;  it  is  due  to 
the  heavy  rains  occurring  at  this  time.  Destructive  inundations  are, 
however,  rarely  caused  by  this  high  water ;  those  best  known  are  the 
inundations  of  1816  and  1864.  In  the  latter  year  the  water  of  the 
Lena,  near  the  city  of  Verkholensk  began  to  rise  rapidly  on  July 
11:  on  the  13th  it  overflowed  the  banks   and  inundated  the  mea- 


RIVERS    OF    SIBERIA.  113 

dows,  islands,  and  the  lower  end  of  the  city ;  on  the  17th  the  river 
was  again  confined  to  its  banks.  The  whole  month  of  July  of  the 
year  1864  was  rather  cold  for  summer  weather ;  the  same  is  true  of  the 
month  of  August,  which  had  a  mean  temperature  of  only  8.4° ;  on 
September  3,  at  5  a.  m.,  the  thermometer  stood  at  — 3.8°.  There 
were  twenty-two  rainy  days  in  July  ;  in  August  it  rained  twelve  times 
and  snowed  twice,  the  water  in  the  Lena  increasing  again  rapidly 
from  August  8  to  14. 

In  the  middle  course  of  the  Lena,  in  the  Kirensk  district,  we  find, 
besides  the  summer  high  water,  overflows  at  the  time  of  the  opening 
of  the  ice.  Thus  in  1870  the  ice  on  the  Lena  near  the  city  of  Kir- 
ensk began  moving  on  April  30 ;  the  river  overflowed  its  banks  and 
inundated  part  of  the  city ;  and  when,  on  May  1,  the  ice  began  also  to 
move  on  the  right-hand  affluent,  Kirenga,  which  empties  into  the 
Lena  near  the  city,  the  water  rose  still  higher,  doing  a  great  deal  of 
damage  in  the  city.  The  overflow  was  especially  great  in  the  villages 
of  the  Vitimsk  district,  situated  along  the  Lena,  below  the  city  of 
Kirensk. 

The  farther  we  go  eastward  into  Siberia  the  less  frequent  and 
destructive  are  the  spring  inundations,  owing  to  the  small  amount  of 
snow  that  falls  during  the  winter  months  in  the  Trans-Baikal  and 
the  Amoor  territory.  In  the  latter  country  deep  snow  is  found  only 
in  the  lower  course  of  the  Amoor.  But,  at  the  time  of  the  summer 
monsoon,  the  abundant  precipitation  causes  heavy  summer  inunda- 
tions. During  the  years  1855  to  1882  eight  great  inundations  were 
observed  in  the  basin  of  the  Amoor ;  the  most  destructive  of  these 
was  the  one  in  1872,  which  came  from  the  upper  course  of  the  Amoor. 
At  Stretensk  the  water  level  reached  its  greatest  height  on  July  9,  at 
Blagovechensk  on  the  15th  and  16th.  At  the  latter  place  the  water 
rose  10  meters  above  the  ordinary  level,  in  spite  of  the  fact  that  the 
river  valley  is  there  rather  open  and  the  banks  of  the  Amoor,  in  par- 
ticular the  left-hand  bank  below  the  city,  are  lowlands.  But,  in  the 
Maly-Khingan  mountains  the  water  in  the  Amoor  rose  16  meters 
above  its  mean  level.  On  July  19  the  water  began  to  fall  near 
Blagovechensk.  Out  of  twenty-seven  settlements  (stanitsa),  situated 
on  the  left  bank  of  the  upper  Amoor,  ten  were  carried  away  by  the 
flood.  A  second,  and  very  considerable,  rise  of  the  waters  of  the 
Amoor  occurred  in  the  month  of  August  of  the  same  year,  coming 
from  the  rivers  Argoon  and  Zeia.  Thus  on  August  9  and  10  the 
water  of  the  Amoor  rose  17.5  meter8(  !)  above  the  ordinary  level  at 
the  Pokrovsky  settlement ;  at  the  city  of  Blagovechensk  the  greatest 
height  of  the  water  occurred  on  August  15  and  16,  but  the  height 
reached  was  less  than  in  July. 

Heavy  floods  were  also  observed  in  the  river  Zeia  in  1861,  when  the 
water  of  this  river  rose  three  times  in  the  course  of  the  same  sum- 


114 


CHICAGO    METEOROLOGICAL    CONGRESS. 


mer — from  June  10  to  13,  from  July  20  to  August  2,  and  from  August 
31  to  September  10. 

In  the  southern  portion  of  Ussurysk  territory  the  heaviest  inunda- 
tions occurred  in  the  years  1861,  1863,  1868,  and  1873.  The  overflows 
of  the  Amoor  begin  usually  after  more  or  less  prolonged  rains.  But 
as  the  amount  of  precipitation  is  not  uniformly  distributed,  the  in- 
undations are  most  heavy  sometimes  in  one,  sometimes  in  another 
part  of  the  Amoor  and  Ussurysk  territory. 

As  regards  the  current  velocity  and  the  discharge  of  th«  Siberian 
rivers,  we  have,  besides  the  scientific  determination  of  these  quanti- 
ties made  by  Dr.  Stelling  for  the  Angara,  some  observations  on  smaller 
rivers,  viz.,  the  Tobol  and  the  Toora.  These  observations  were  made 
with  a  view  to  decide  the  question  as  to  the  sufficiency  of  the  supply 
of  water  in  these  rivers  for  navigation  purposes.  Observatfons  were 
also  made  on  some  other  small  rivers,  viz.,  the  Oziornaia,  Lomovataia, 
Jazevaia,  Maly  Kas,  and  Bolshoi  Kas,  in  connection  with  the  investi- 
gations for  the  purpose  of  connecting  the  Obi  with  the  Yenisei. 

The  observations  of  Dr.  Stelling  at  Irkutsk  showed  that  the  mean 
water  level  of  the  Angara  at  this  point  has  an  elevation  of  453.3 
meters.     He  also  found  the  results  tabulated  as  follows : 


c  ^  '^  i: 

e!  O  c  2 
=  «.=  O- 


u 

43 

Velocity 

O.    . 

of  current,  in 

B 

■a  I- 

S" 

meters  per 
second. 

*3  « 

«J   ^  (T* 

J5 

CD   P 

<S  =  m 

c 

•o 

ta 

tS 

X 

^ 

O 

^-fc 

a 

.■?27 

7-15 

1.365 

1.67 

1.98 

577 

5-44 

1.905 

1.22 

1.90 

597 

6.o6 

2,219 

1.26 

6oo 

5-47 

1,920 

0.89 

At  the  Znamensky  Convent,  below  the  month  of  the 
river  Irkoot 

At  the  Troitsky  Ferry 

At  the  same  place,  when  the  water  was  higher,  July 
21 

Same  place,  under  the  ice 


2,276 
2.321 


2.793 
1,709 


At  the  Troitsky  Ferry,  where  the  current  velocity  and  the  depth 
of  the  river  are  less,  while  the  area  of  the  cross-section  is  greater, 
more  water  flows  by  than  farther  down  the  river,  at  the  Znamensky 
Convent.  When  the  water-level  is  higher,  the  dimensions  of  the 
river,  its  depth,  are  increased,  and  so  is  the  velocity  of  the  current 
and  the  quantity  of  water  flowing  by  (discharge). 

It  is  to  be  hoped  that,  in  connection  with  the  proposed  railway 
line  through  Siberia,  the  Ministry  of  Roads  of  Communication  will 
at  once  institute  investigations  of  a  similar  kind  for  the  other  im- 
portant rivers  of  Siberia. 

The  annual  discharge  of  the  Angara  shows  a  maximum  in  the  fall 
and  a  minimum  in  the  spring. 

The  amount  of  water  carried  by  the  Angara  in  the  year  1887  was, 
according  to  the  results  obtained  by  Dr.  Stelling,  in  cubic  kilometers, 
as  follows : 


KIVERS    OF    SIBERIA. 

Discharge  of  the  Angara  for  1887. 


115 


Period. 


Discharge  per- 


Month. 


Day. 


January  

February  .. 

March 

April 

May 

June 

July 

August 

September. 

October 

November .. 
December  . . 


7.056 
5.642 
4.920 
4.629 
4.976 
5-262 
6.442 
6.950 

7-3" 
7. 161 
6.069 
5-475 


o. 2276 
0.2015 
o. 1587 
o- 1543 
o. 1605 
o- 1754 
o. 2078 
o. 2242 
o- 2437 
0.2310 
o. 2023 
0. 1766 


Total  annual  discharge  . 
Average  daily  discharge 


71-893 


o. 1970 


For  the  smaller  rivers  mentioned  above,  the  following  brief  data 
are  available  with  regard  to  the  current  velocity  and  the  discharge : 


Rivera. 

Fall  of  the  river  in 
the  whole  investi- 
gated distance,   in 
meters. 

Mean  current  veloc- 
ity, in  meters  per 
second. 

Discharge  per  second, 
in  cubic  meters. 

Toora 

7-6        ^ 
2.6 
.... 

12.3 

3-4 

15-2 
39-8 

0.23 
0.46 

0.  II 
0.20 

O.03 

246.70 

357-40 

17-50 

9.00 

.         {o.84» 

(0.45'' 

I  8. 90* 

Tobol 

Oziornaia 

Lomovataia 

Yazevaia 

Maly-Kas 

Bolsboi-Kas 

»  Upper  portion. 


*  Lower  portion. 


In  concluding,  the  regret  must  be  expressed  that  at  present  only  a 
very  small  number  of  stations,  separated  by  immense  distances,  exist 
in  Siberia  for  meteorological  investigations ;  and  that  the  number 
of  stations  having  observations  for  a  longer  period  is  still  more 
limited.  It  is  to  be  hoped  that  the  Magneto-meteorological  Observa- 
tory established  at  Irkutsk  in  1886  will  do  all  in  its  power  to  extend 
the  sphere  of  its  activity,  and  that  it  will  turn  its  attention  also  to 
the  investigation  of  the  rivers.  For  there  are  many  questions  con- 
nected with  the  rivers  still  awaiting  a  final  solution ;  such,  for 
instance,  as  the  cause  of  the  formation  on  many  Siberian  rivers, 
during  the  severest  cold,  of  so-called  "  propariny,"  i.  e.,  open  places 
in  the  ice,  which  may  sometimes  for  a  while  become  covered  with  a 
very  thin  crust  of  ice ;  the  formation  of  foam  on  the  rivers ;  the 
causes  why  some  rivers  do  not  freeze ;  the  formation  and  thickness 
of  the  ice  on  rivers,  and  in  particular  on  Lake  Baikal,  where,  as  is 
well  known,  a  regular  cannonade  is  sometimes  heard  in  winter, 
arising  from  the  constant  formation  of  fissures  in  the  ice,  which 
afterward  move  away ;  the  temperature  of  the  water  in  the  rivers ; 
the  degree  to  which  the  soil  freezes ;  the  snow  sheet  covering  the 
country  in  winter;  and,  so  on.  All  these  are  problems  hardly  as  yet 
touched  by  investigation. 


116 


CHICAGO    METEOROLOGICAL   CONGRESS. 


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THE    RHINE.  117 


6— REGIMEN  OF  THE  RHINE  REGION:  HIGH- WATER  PHE- 
NOMENA AND  THEIR  PREDICTION. 

M.  VON  Tein. 

The  regimen  of  a  river,  as  well  as  the  appearance  and  progress  of 
high-water  phenomena,  it  is  known,  bear  a  close  relation  to  the  physi- 
cal characteristics  of  the  region,  particularly  the  relief  of  the  ground, 
the  extent  of  the  drainage  area  and  the  climatic  elements  dependent 
on  the  former,  especially  the  distribution  of  the  rainfall.  A  con- 
sideration of  the  hydrological  phenomena  of  a  region  requires,  there- 
fore, at  first  a  glance  at  its  general  physical  characteristics. 

The  Rhine,  although  it  drains  scarcely  an  area  of  160,000  square 
kilometers  with  its  tributaries,  extends  diagonally  through  the  prin- 
cipal jjarts  of  middle  Europe,  the  Alps,  the  mountain  region  of  central 
Germany,  and  the  Netherland  lowlands.  Its  drainage  area  has  there- 
fore an  uncommonly  great  variety  of  relief.  From  the  chain  of  the 
central  Alps,  towering  to  a  height  of  4,000  meters,  forming  the  south- 
ern boundary,  the  region  falls  toward  the  Swiss  and  upper  Swabian 
highland,  of  which  the  average  elevation  is  500  meters,  and  rises 
again  to  over  1,000  meters  in  the  Jura,  the  Black  Forest,  and  the 
Vosges,  the  most  considerable  elevations  of  which  bound  it  on  the  west 
and  north.  Sunk  between  the  Black  Forest  and  the  Vosges  lies  the 
upper  Rhine  lowlands  traversed  by  the  Rhine,  while  on  the  verge  of 
the  mountain  range  roundabout  spreads  extensive  terrace  and  the  fiat 
valleys,  forming  the  region  of  the  entrance  of  the  great  central  moun- 
tain rivers — the  Neckar,  Main,  and  Moselle. 

On  the  north  the  mountains  of  the  lower  Rhine,  traversed  by  the 
Rhine  in  a  deeply  eroded  valley,  shut  off  the  central  mountains 
toward  the  north  German  highland  to  which  the  lowest  parts  of  the 
drainage  area  belong.  The  Rhine  flows  here  in  its  upper  course 
through  high  mountains,  a  high  tableland,  and  the  central  mountain 
range ;  in  its  middle  course  through  a  low  plain  and  then,  for  the 
first  time,  after  breaking  through  the  great  chain  of  the  central 
mountain  range,  begins  its  lower  course  with  its  entrance  into  the 
north  German  lowlands. 

The  grouping  of  these  surfaces  forms  a  many-branching  river 
system  among  the  streams  of  the  Alps,  of  the  central  mountain 
region,  and  the  lowlands,  a  distinction  which,  for  the  regimen  of  the 
drainage  area,  is  of  the  greatest  significance. 

The  Rhine  assembles  the  streams  of  the  Alpine  country  and  the 
borders  where  it  leaves  the  Swiss  highland ;  here  the  Alpine  part  of 
the  tributary  region  ends,  which,  with  considerable  rainfall,  has  also 
great  capacity  for  retaining  water. 

The  precipitation  in  the  Alps  for  the  greater  part  of  the  year  being 


118  CHICAGO    METEOROLOGICAL   CONGRESS. 

in  a  solid  form,  is  stored  up  in  the  winter  and  in  the  warm  season  is 
given  up  as  melted  snow  more  or  less  freely,  and  the  run-off  is  modi- 
fied by  a  considerable  number  of  lakes  around  the  border  of  the  Alps. 
The  region  of  the  central  mountain  rivers  begins  with  the  breaking 
of  the  Rhine  through  the  Jura  or  with  its  entrance  into  the  uppe 
Rhine  lowlands  at  Basel.  At  first  the  river  receives  only  small 
streams,  for,  on  both  sides  parallel  to  it  and  only  a  short  distance 
from  it,  the  Black  Forest  range  and  the  Vosges  turn  their  steep  flanks 
toward  it,  while  on  the  other  side  they  drain  off  toward  the  Neckar 
and  the  Moselle.  The  Rhine  in  this,  the  second  principal  part  of  its 
course,  traverses  a  distance  of  more  than  300  kilometers  before  the 
great  central  mountain  river,  the  Neckar,  empties  into  it,  and  then, 
in  relatively  rapid  succession  in  a  distance  of  about  150  kilometers 
by  the  river,  there  come  into  it  the  Main,  the  Nahe,  the  Lahn,  and 
the  Moselle.  In  the  region  of  these  central  mountain  range  rivers, 
the  Black  Forest  range,  and  the  Vosges,  the  rainfall  is  still  very  con- 
siderable. The  snow  covering  in  the  course  of  the  winter,  from 
repeated  thaws  and  according  to  its  height  and  density  and  the 
accompanying  circumstances  of  its  melting,  occasionally  produces 
great  floods  in  the  streams  in  a  short  time.  Persistent  rain  and 
thunderstorms  often  carry  the  wet  period  into  midsummer,  and  in 
autumn  in  the  high  central  mountain  region  the  precipitation  reaches 
its  maximum ;  the  feeding  out  of  water  to  streams  diminishes  very 
considerably  in  consequence  of  the  great  loss  of  water  by  evaporation 
and  absorption  by  plants.  The  third  division  of  the  Rhine  drainage 
area,  comprising  the  streams  of  the  lowland  from  about  the  mouth 
of  the  river  up  to  the  lower  Rhine  Mountains,  is  relatively  small  and 
not  of  much  importance  as  regards  the  water  which  flows  from  it  into 
the  Rhine.  The  region  is  under  the  moderating  influence  of  the 
ocean  climate,  so  that  sudden  changes  of  weather  and  their  conse- 
quences are  scarcely  perceptible  in  the  rivers. 

The  changes  in  river  stage  along  the  Rhine  occur  as  follows  :  along 
the  upper  course  and  down  to  the  Neckar  the  flow  from  the  Black 
Forest  range  and  the  Vosges  is,  as  a  rule,  not  considerable  enough  to 
make  any  appreciable  change ;  it  is  completely  controlled  by  the 
water  from  the  high  mountain  region ;  very  little  water  comes  in 
during  the  winter ;  there  is  considerable  addition  of  water  in  the 
spring  with  the  disappearance  of  the  snow  on  the  lower  mountains ; 
there  is  an  increased  flow  at  the  beginning  of  summer  as  the  melting 
advances  up  the  high  mountains ;  and  finally,  again  a  diminishing 
supply  of  water,  until  toward  spring,  in  spite  of  the  continuing  addi- 
tions of  glacier  water.  There  is,  therefore,  a  tolerably  steady  increase 
from  winter,  not,  however,  without  this  regular  course  being  varied 
and  broken  into  at  times  by  heavy  floods  due  to  great  rainfall  such 
as  often  accompanies  the  Fohn  wind.     In  the  section  of  the  Rhine 


THE    RHINE.  119 

between  the  Neckar  and  the  Moselle,  under  the  influence  of  the  great 
central  mountain  range  rivers,  a  change  occurs  in  the  order  of  river- 
stage  variation  which  begins  to  be  first  apparent  at  the  entrance  of 
the  Neckar,  and  still  more  so  at  Mainz  after  the  entrance  of  the  Main. 
Below  the  mouth  of  the  Moselle  there  is  a  complete  reversal  of  con- 
ditions. The  diminished  supply  of  water  toward  the  end  of  winter 
becomes  apparent  at  Mainz  as  a  secondary  maximum ;  below  the 
mouth  of  the  Moselle  it  reaches  the  summit  of  the  annual  curve ;  at 
this  point,  on  the  contrary,  the  summer  high  water  of  the  upper 
Rhine,  which  is  seldom  strongly  reinforced  from  the  central  moun- 
tain range  region,  sinks  to  a  moderate  rise,  while  on  the  other  hand 
in  February  and  March,  among  the  poorest  months  in  the  year  in 
water  above  the  entrance  of  the  Neckar  at  the  mouth  of  the  Moselle, 
the  highest  stages  occur.  In  the  lower  Rhine  the  stages  of  water  thus 
produced  by  the  Neckar,  Main,  and  Moselle  no  longer  change,  but 
are  rather  intensified  by  the  tributaries. 

A  like  great  difference  in  the  behavior  of  the  various  parts  of  the 
Rhine  appears,  especially  during  the  prevalence  of  high  water.  It  is 
in  a  measure  a  rule,  that  considerable  flood  waves  in  the  upper  part 
of  the  drainage  area  appear  along  the  middle  and  lower  courses  as 
inconsiderable  rises,  and  that  again,  flood  phenomena  appear  in  which 
the  upper  courses  of  the  river  have  no  part.  The  absolute  high 
waters  observed  so  far  in  the  various  divisions  of  the  river  have  oc- 
curred in  entirely  different  periods  of  high  water.  Excessive  arid 
disastrous  high  waters  affecting  the  river  in  all  its  parts  scarcely  ever 
occur ;  at  least  they  are  exceedingly  rare.  The  high  water  is  always 
caused  by  extraordinarily  great  rainfalls,  which,  as  experience  shows, 
occur  over  only  very  restricted  areas  and  in  isolated  cases,  when,  with 
great  downpour,  melting  of  snow  occurs  simultaneously  over  a  great 
part  of  the  drainage  area ;  under  these  circumstances  the  tributary 
basins  cause  various  combinations  of  high-water  waves.  It  frequently 
happens  that  the  highest  stage  of  a  rise  in  the  middle  Rhine  occurs 
when  at  the  same  time  the  upper  Rhine  is  still  rising  and  the  apex  of 
the  rise  comes  down  as  far  as  the  entrance  of  the  Neckar,  and  by  that 
time  the  high  water  in  the  middle  and  lower  Rhine  is  long  past.  The 
behavior  of  the  tributaries  has  a  very  important  bearing  on  the  course 
of  high  water  in  the  main  stream,  especially  if  the  flood  waves  from 
the  last  two  great  tributaries,  the  Main  and  Moselle,  both  of  which 
in  length  of  course,  extent,  and  nature  of  drainage  area  show  great 
similarity,  succeed  each  other  in  such  a  way  that  the  wave  from  the 
Main  comes  in  on  the  crest  of  the  wave  from  the  Moselle  at  Coblentz. 
The  subsequent  flood  wave  from  the  upper  Rhine  causes  in  the  middle 
and  lower  Rhine,  and  in  fact  from  the  Neckar  down,  only  a  delay  in 
the  recession  of  the  water. 

It  is  a  fact  well  known  from  experience,  and  it  finds  explanation  in 


120  CHICAGO    METEOROLOGICAL    CONGRESS. 

the  preceding  remarks,  that  the  Rhine  region,  as  compared  with  the 
neighboring  regions,  is  naturally  protected  in  a  higher  degree  against 
the  frequent  occurrence  of  disastrous  high  waters,  because  many  oppo- 
site conditions  must  act  together  to  produce  such  a  high  water .^  Never- 
theless, the  occurrence  of  such  an  event  in  such  a  closely  cultivated 
region  as  this  is,  means,  in  every  case,  a  great  damage  to  agricultural 
interests.  Ten  years  ago,  after  the  memorable  high  water  in  the 
winter  of  1882-83,  the  German  Imperial  Government  established  a 
commission  to  investigate  the  Rhine  and  consider  the  best  methods 
of  artificial  protection  against  floods.  This  commission  reported  in 
1891  to  the  Chancellor  of  the  Empire  the  results  of  its  eight  years' 
activity.  In  the  report  the  fact  is  emphasized  that,  in  view  of  the 
dense  population  and  minutely  cultivated  parts,  it  is  out  of  the  ques- 
tion to  try  combating  the  might  of  high  waters  by  measures  calculated 
to  restrain  the  waters  on  a  large  scale,  aside  from  the  fact  of  the  enor- 
mous expense  of  such  a  proceeding — out  of  all  proportion  to  the  ad- 
vantages to  be  derived — and  other  vested  interests  of  the  population 
of  the  region  would  be  thereby  greatly  damaged.  High  water  protec- 
tion, in  addition  to  measures  of  protection  by  a  suitable  treatment  of 
the  course  of  the  river,  and  by  the  leveeing  of  frontages  threatened  by 
floods,  must  remain  limited  to  deriving  a  correct  knowledge  as  to 
what  must  be  withstood  from  the  beginning  and  throughout  the 
course  of  dangerous  rises.  This  knowledge  consists,  up  to  the  present 
time,  in  a  carefully  organized  service  for  the  dissemination  of  infor- 
mation regarding  high  water,  by  telegraph  principally.  What  still 
remains  in  this  domain  worth  gaining,  and  which  the  commission  in 
investigating  the  Rhine  proposes  to  attain,  is  the  numerical  determi- 
nation of  water  heights  to  be  reached  during  rises  along  the  middle 
and  lower  courses  of  the  Rhine,  and  along  the  upper  course  and  its 
larger  tributaries,  and  also  the  establishment  of  a  system  of  high  water 
predictions.  This,  for  the  population  interested,  would  doubtless  be 
more  valuable  than  simply  information  as  to  the  stages  of  water  at 
places  on  the  river  above.  Considering  the  extraordinary  difficulties 
in  the  way  of  forecasting,  in  view  of  the  changing  regimen  of  the  river 
just  described  and  the  complex  phenomenon  of  a  high  water,  and  the 
lack  of  previous  hydrological  investigation  (which  heightens  the  diffi- 
culty), high  water  predictions  have  not  yet  been  attempted.  In  the 
year  1886,  on  the  suggestion  of  the  Imperial  Commission  before  men- 
tioned, the  Central  Bureau  fur  Meteorologie  und  Hydrologie  of  Baden, 

^  The  regimen  of  the  Rhine  region  and  the  behavior  of  the  river  during  high  water 
is  treated  of  very  full}'  in  the  work  J)er  Eheinstrom  und  seine  wichtigsten  Nebenfliisse, 
Berlin,  1889,  issued  from  the  Central  Bureau  fur  Meteorologie  und  Hydrographie  in 
the  Grand  Duchy  of  Baden.  The  high  waters  occurring  in  this  century  are  treated 
of  very  fully  in  the  first  volume  of  Ergehnisse  der  Untersuchung  der  Hochwasserver- 
haltnisse  im  Deutscheti  Rheingebiet,  Berlin,  1891. 


THE    NILE.  121 


at  Carlsruhe,  was  designated  as  the  proper  institution  to  be  entrusted 
with  the  investigation  of  hydrological  phenomena  during  the  incep- 
tion and  progress  of  great  rises  in  the  Rhine  and  its  tributaries,  so 
as  to  lay  a  firm,  scientific  foundation,  on  which,  perhaps,  satisfactory 
high-water  predictions  may  in  the  future  be  based. 


7— THE  NILE. 

W.    WiLLCOCKS,    M.   I.    C.    E. 

The  recent  explorations  of  Lugard  and  Baumann  have  completed 
the  work  originated  by  Burton  and  carried  on  by  Speke,  Grant, 
Baker,  Stanley,  Gordon,  Junker,  and  Schweinfurth,  and  we  can  now 
follow  the  course  of  the  Nile  from  its  springs  far  south  of  the 
equator  to  its  termination  north  of  the  thirtieth  parallel  of  latitude. 
A  river  so  regular  and  gentle  in  its  movements  as  the  Egyptian  Nile 
can  only  be  understood  after  a  study  of  its  sources  of  supply,  and  the 
early  part  of  this  paper  must,  therefore,  be  devoted  to  the  hydrology  of 
the  Nile  Valley.  On  the  accompanying  plan  and  longitudinal  section 
are  detailed  the  observed  times  and  heights  of  high  and  low  supply, 
and  the  times  and  proportions  of  rainfall.  From  the  sea  to  Wady 
Haifa  the  Egyptian  Irrigation  Service  has  supplied  the  figures ;  from 
Wady  Haifa  to  Khartoum  Sir  John  Fowler's  surveys  and  levels 
have  been  used,  with  a  correction  of  13  meters  to  suit  the  figures  of 
the  irrigation  department  at  Wady  Haifa;  while  to  the  south  of 
Khartoum  the  distances  and  heights  have  been  taken  from  the  obser- 
vations of  Gordon  Pasha's  staff  when  he  was  governor  of  the  Soudan. 
To  Lake  Victoria  a  mean  level  has  been  applied.  I  take  this  oppor- 
tunity of  acknowledging  my  thanks  to  Bonola  Bey,  the  Secretary  of 
the  Khedivial  Geographical  Society  of  Cairo,  for  the  assistance  I 
have  received  from  him.  I  am  at  the  present  moment  engaged  in 
making  a  stud}"  of  the  Nile  for  the  Egyptian  Government.  This 
study  will  not  be  completed  before  the  end  of  December,  but  on  the 
invitation  of  your  committee,  with  the  consent  of  Mr.,  Garstin,  Under 
Secretary  of  State  for  Public  Works  in  Egypt,  I  have  collected  all 
the  information  which  is  at  my  disposal  to-day  and  have  embodied 
it  in  this  paper. 

The  Nile  drains  nearly  the  whole  of  northeastern  Africa,  an  -area 
comprising  3,110,000  square  kilometers.  Its  main  tributary,  the 
White  Nile,  has  its  source  to  the  south  of  Lake  Victoria  and  has  trav- 
ersed over  3,500  kilometers  before  it  is  joined  by  the  Blue  Nile  at 
Khartoum.  From  the  junction  onward  the  river  is  known  as  the 
Nile,  and  after  a  farther  course  of  3,000  kilometers  flows  into  the 
Mediterranean  Sea  by  the  Rosetta  and  Damietta  mouths. 

Lake  Victoria,  covering  an  area  of  70,000  square  kilometers  is  the 


122  CHICAGO    METEOROLOGICAL   CONGRESS. 

first  reservoir  of  the  Nile.  The  equator  passes  through  this  lake, 
which  lies  in  the  region  of  almost  perpetual  rains  and  receives  an 
excessive  supply  of  water  from  its  western  tributaries,  from  subsoil 
springs,  and  heavy  rainfall.  Stanley  considered  the  discharge  of  the 
White  Nile  as  it  left  Lake  Victoria  as  one-third  greater  than  that  of 
the  Tangourie,  the  principal  affluent  of  the  lake.  Judging  from  re- 
corded observations  farther  down  the  river,  the  mean  discharge  of  the 
lake  is  probably  750  cubic  meters  per  second.  Shortly  after  leaving 
Lake  Victoria,  the  White  Nile  descends  the  Ripon  Falls  on  a  width 
of  400  meters  and  a  drop  of  4  meters.  Lake  Victoria  lies  about  1,130 
meters  above  sea  level  and  is  500  meters  higher  than  Lake  Albert. 
Between  these  lakes,  on  a  distance  of  480  kilometers  the  White  Nile 
(known  here  as  the  Somerset)  traverses  at  first  the  succession  of 
swamps  known  as  the  Ibrahimia  Lake,  and  then  taking  the  character 
of  a  mountain  torrent  precipitates  itself  into  the  southeast  corner  of 
Lake  Albert.  The  survey  of  Lake  Albert,  which  has  an  area  of  4,500 
square  kilometers,  was  made  in  1877  by  Mason  Bey,  and  he  recorded 
the  fact  that  the  lake  was  1.20  meters  below  its  high-water  level. 
The  rainfall  of  that  year  was  deficient  in  the  whole  of  the  Nile  Val- 
ley, and  the  summer  supply  of  the  Nile  was  the  lowest  of  which  there 
is  any  record.  In  July,  1892,  Capt.  Lugard  noticed  that  Lake  Vic- 
toria was  2  meters  above  its  normal  level  after  the  heavy  rains  of  that 
year,  and  the  summer  supply  of  the  Nile  in  1893  is  so  high  that  it 
has  only  once  been  exceeded,  according  to  our  records.  Lake  Edward, 
with  an  area  of  5,000  square  kilometers  and  a  height  above  sea  level 
of  880  meters,  is  a  feeder  of  Lake  Albert.  After  leaving  Lake  Albert 
the  White  Nile  flows  for  200  kilometers  in  a  deep,  broad  arm  with 
scarcely  any  slope  and  scarcely  any  velocity  as  far  as  Duffle,  and  then 
after  a  short,  troubled  course  tosses  over  the  Fola  rapids  on  a  width 
of  90  meters,  and  continues  as  a  torrent  for  another  200  kilometers  to 
a  short  distance  south  of  Gondokoro.  At  Gondokoro  the  river  is  2 
meters  deep  at  low  water,  and  only  4.50  meters  deep  in  flood,  the  dis- 
charge ranging  between  500  and  1,600  cubic  meters  per  second.  The 
regulating  effect  of  the  great  lakes  is  well  felt  here.  We  are  indebted 
to  Emin  Pasha  for  this  information.  It  is  one  of  the  keys  for  under- 
standing the  flow  of  the  Nile,  and  will  be  dwelt  on  later  in  this  paper. 
At  Gondokoro  the  river  is  at  the  lowest  in  winter,  it  begins  to  rise 
about  April  15,  and  reaches  its  maximum  between  August  15  and  30. 
From  Gondokoro  to  Bor,  a  distance  of  about  120  kilometers,  the 
river  keeps  in  one  channel  and  has  a  rapid  fall,  while  from  Bor  to 
the  mouth  of  the  Gazelle  River,  on  a  farther  reach  of  380  kilometers, 
the  river  divides  into  numerous  channels  and  has  a  very  feeble  slope. 
The  main  channel  is  known  as  the  Bahr  el  Gebel  (the  mountain 
stream),  and  is  the  one  always  used  for  navigation.  In  this  reach 
are  the  "  sadds  "  or  dams  of  living  vegetation  which,  at  times,  are 


THE    JflLE.  123 

capable  of  barring  the  surface  and  completely  blocking  navigation. 
The  Gazelle  River  joins  the  White  Nile  on  its  left  bank  and  has  a 
feeble  discharge  in  summer,  but  exceeds  the  Bahr  el  Gebel  in  flood. 
At  the  junction  of  the  Gazelle  River  and  the  White  Nile  is  a  lake  of 
an  area  of  some  150  square  kilometers  in  summer.  During  this 
latter  period,  in  years  of  scanty  rainfall,  all  this  part  of  the  river 
acts  as  an  evaporating  basin  and  a  source  of  loss  to  the  Nile.  The 
waters  of  the  river  likewise  become  polluted  here  with  decaying  vege- 
table matter  which,  at  certain  times  of  the  year,  imparts  a  green  color 
to  the  Nile  as  far  north  as  Cairo.  One  hundred  kilometers  below  the 
Gazelle  River  the  White  Nile  is  joined  by  the  Saubat  River  on  its 
right  bank.  During  flood  this  river  has  a  discharge  nearly  equal  to 
that  of  the  White  Nile  above  the  junction,  while  in  summer  it  has  a 
feeble  discharge  and  is  occasionally  quite  dry.  From  the  junction  of 
the  Saubat  to  Khartoum,  on  a  length  of  900  kilometers,  the  White 
Nile  has  a  mean  width  of  1,700  meters,  a  depth  varying  from  5  meters 
in  low  supply  to  7.5  meters  in  flood,  and  a  sluggish  stream.  The 
action  of  the  current  is  always  on  the  right  bank  owing  to  the  pre- 
vailing northwest  Avinds,  and  this  action  is  continued  during  the 
whole  of  the  remaining  course  of  the  river  as  far  as  the  sea.  The 
soil  from  the  Saubat  River  to  Khartoum  is  light  and  friable,  and  the 
White  Nile,  in  spite  of  its  moderate  velocity,  has  a  width  160  limes 
its  depth  in  flood. 

At  a  point  3,009  kilometers  from  the  sea,  and  390  meters  above  it, 
is  the  town  of  Khartoum,  where  the  Blue  Nile  from  Abyssinia  joins 
the  White  Nile.  The  Blue  Nile  has  its  sources  in  the  mountains  of 
Abyssinia,  where  Lake  Tsana — with  an  area  of  3,000  square  kilometers 
and  height  above  sea  level  of  1,780  meters — is  another  reservoir  of  the 
Nile.  The  Blue  Nile  has  a  length  of  1,350  kilometers.  This  river  is 
comparatively  clear  in  summer,  but  during  flood,  i.  g.,  from  the  begin- 
ning of  June  to  the  end  of  October,  it  is  of  a  reddish-brown  color, 
highly  charged  with  alluvium.  The  Khartoum  Nile  gauge,  which  was 
read  from  1869  to  1883,  used  to  stand  on  the  Blue  Nile  about  5  kilo- 
meters above  its  junction  with  the  White  Nile,  and  its  recorded  read- 
ing are  not  exact  records  of  the  Nile.  In  flood  the  discharges  of  the 
two  rivers  are  equal,  but  in  summer  the  White  Nile  is  the  main  source 
of  supply.  The  Nile  here  has  a  mean  range  of  6.50  meters  between 
high  and  low  supply,  with  a  maximum  of  7.80  meters  and  a  minimum 
of  5.30  meters.  From  comparisons  with  the  Assuan  gauge,  and'  ob- 
served discharges  referred  to  the  Khartoum  gauge,  I  calculate  that 
the  high  supply  varies  between  12,900  and  5,200  cubic  meters  per 
second,  with  a  mean  discharge  of  8,000  cubic  meters  per  second,  while 
the  low  supply  varies  between  1,500  and  320  cubic  meters  per  second, 
with  a  mean  discharge  of  550  cubic  meters  per  second.  April  is  the 
lowest  month  and  September  the  highest. 


124  CHICAGO    METEOROLOGICAL   CONGRESS. 

At  a  distance  of  90  kilometers  down  stream  of  Khartoum  is  the 
sixth  cataract.  Here  the  Nile  descends  6  meters  on  a  length  of  18,000 
meters.  At  a  distance  of  320  kilometers  from  Khartoum  the  Nile  is 
joined  by  the  Atbara  River.  This  latter  is  another  stream  fed  by  the 
Abyssinian  torrents,  and  though  dry  in  summer  is  a  considerable 
river  in  flood.  Heavily  charged  with  volcanic  detritus  it  provides  the 
greater  part  of  the  rich,  fertilizing  mud  which  the  Nile  carries  in 
flood.  The  Atbara  has  a  range  of  8  meters,  and  from  calculations 
and  comparisons  I  estimate  that  its  floods  range  between  4,900  and 
1,600  cubic  meters  per  second,  with  a  mean  high  flood  of  3,400  cubic 
meters  per  second.  It  is  in  flood  from  July  to  October,  with  its  ordi- 
nary maximum  in  August.  Below  the  Atbara  junction  the  Nile  has 
no  tributary,  and  flows  throughout  its  2,700  kilometers  to  the  sea  a 
solitary  stream.  Traversing  one  of  the  greatest  deserts  on  the  globe, 
it  is  the  sole  source  of  life  and  vigor  to  whatever  exists  on  its  banks. 

Twenty-four  kilometers  downstream  of  the  Atbara  junction  is  Ber- 
ber, and  45  kilometers  downstream  of  Berber  is  the  beginning  of  the 
fifth  cataract,  which  has  a  length  of  160  kilometers  and  drop  of  66 
meters,  with  three  principal  rapids,  the  Solimania,  Baggara,  and 
Mograt.  The  village  of  Abu  Hamed  is  situated  at  the  foot  of  this 
cataract.  Between  Abu  Hamed  and  Dongola  is  the  fourth  cataract, 
which  begins  at  a  point  100  kilometers  downstream  of  Abu  Hamed, 
and  has  a  length  of  110  kilometers,  with  a  drop  of  49  meters.  In 
this  series  of  rapids  are  the  Um  Der^s  and  Guerendid.  Between  the 
fourth  and  third  cataracts  is  a  reach  of  310  kilometers  on  a  slope  of 
1  :  12,000.  On  this  reach  is  the  town  of  Dongola.  The  third  cata- 
ract has  a  length  of  70  kilometers  and  drop  of  11  meters  with  the 
Hannek  and  Kaibar  rapids,  surveyed  and  leveled  by  De  Gottberg  in 
1857.  Upstream  of  the  Hannek  rapid  on  the  left  bank  of  the  Nile 
is  the  termination  of  the  long  depression  in  the  deserts,  which  goes 
by  the  name  of  Wady  el  Kab,  and  is  considered  by  many  as  lower 
than  the  Nile  valley.  Between  the  third  and  second  cataracts  is  an 
ordinary  reach  of  130  kilometers.  West  of  this  part  of  the  Nile  are 
the  Selima  Wells,  and,  according  to  some  travellers,  an  old  abandoned 
course  of  the  Nile  slightly  above  the  present  high  level  of  the  river. 
This  waterless  river  terminates  in  the  Oasis  of  Berys,  which  is  separ- 
ated from  the  Khargeh  Oasis  by  a  limestone  ridge. 

The  second  cataract,  known  as  the  "Batn  el  Haggar,"  has  a  length 
of  200  kilometers  and  drop  of  66  meters  with  the  rapids  of  Amara, 
Dfil,  Semna,  and  Abka.  At  Semna  are  the  rocks  where  Lepsius  dis- 
covered the  Nile  gauges  cut  by  one  of  the  Pharoahs  some  4,000  years 
ago.  The  Nile  flood  then  was  8  meters  higher  at  this  spot  than  what 
it  is  to-day.  The  erosion  which  has  taken  place  here  is  very  excessive 
compared  with  that  between  the  second  and  first  cataracts  and  at  the 
first  cataract.     At  Wady  Haifa,  near  the  foot  of  the  second  cataract, 


THE    NILE.  125 

a  masonry  gauge,  divided  into  meters,  has  been  erected  and  read  since 
1877.  Between  the  first  and  second  cataracts  the  Nile  has  a  length 
of  350  kilometers  and  slope  of  1  :  12,500.  The  mean  width  of  the 
river  is  500  meters,  and  the  mean  depths  in  flood  and  summer  are  9 
and  2  meters.  The  velocity  in  summer  falls  to  50  centimeters  per 
second  and  rises  to  2  meters  per  second  in  flood.  The  river  in  this 
reach  is  generally  within  sandstone,  and  the  greater  part  is  provided 
with  gigantic  spurs  on  both  banks.  These  spurs  perform  the  double 
work  of  collecting  soil  on  the  sides  in  flood  and  training  the  river  in 
summer.  They  were  probably  put  up  by  the  great  Rameses  3,000 
years  ago,  as  some  of  the  most  massive  of  them  have  evidently  been 
constructed  to  turn  the  river  on  a  curve  out  of  its  natural  channel 
on  to  the  opposite  side  in  order  to  secure  deep  water  in  front  of  the 
temple  of  Jerf  Husain  ("Jerf"  means  steep,  scoured  bank).  The 
spurs  have  been  constructed  with  care,  and,  as  the  courses  of  roughly 
dressed  stone  can  be  examined  at  fairly  low  water  (I  have  never  seen 
them  at  absolutely  low  water),  it  is  evident  that  there  has  been  no 
great  degradation  of  the  })ed  during  the  last  2,000  or  3,000  years. 
The  first,  or  AssuAn,  cataract  has  a  drop  of  5  meters  on  a  length  of  5 
kilometers. 

From  Khartoum  to  Assuan,  on  a  total  length  of  1,809  kilometers, 
there  are  563  kilometers  of  so-called  cataracts  with  a  total  drop  of 
203  meters,  and  1,246  kilometers  of  ordinary  channel  with  a  total 
drop  of  83  meters 

At  the  foot  of  the  first  cataract,  opposite  the  town  of  Assuan,  on 
the  island  of  Elephantine,  has  stood  a  Nile  gauge  from  very  ancient 
times.  An  officer  belonging  to  the  Roman  garrison  in  the  time  of 
the  Emperor  Severus,  marked  an  extraordinary  high  flood  on  the 
gauge.  The  maximum  flood  mark  at  the  time  of  the  visit  of  Napo- 
leon's French  savants  was,  however,  2.11  meters  higher  than  the  above 
As  the  middle  of  Severus  reign  was  A.  D.  200,  and  the  visit  of  the 
French  savants  A.  D.  1800,  they  concluded  that  the  bed  and  banks  of 
the  Nile  had  risen  2.11  meters  in  1,600  years,  or  0.132  meters  per  100 
years.  The  new  gauge,  divided  into  cubits  and  twenty-fourths,  was 
erected  in  1869  and  has  been  recorded  daily  since  then  (a  cubit  =  54 
centimeters). 

From  Assuan  to  the  Barrage  the  length  of  the  river  is  970  kilome- 
ters, and  the  slope  1 :  12,900,  while  the  mean  fall  of  the  valley  is 
1 :  10,800 ;  from  the  Barrages,  at  the  head  of  the  Delta  proper,  the  dis- 
tance to  the  sea  down  either  branch  is  236  kilometers,  with  the  same 
slope  as  before.  The  mean  width  of  the  main  Nile  is  820  meters,  and 
the  mean  depth  in  flood  8.5  meters.  On  the  Rosetta  branch  the  mean 
width  is  500  meters  and  depth  8  meters,  while  the  Damietta  branch 
has  a  mean  width  of  350  meters  and  mean  depth  of  7.5  meters.  The 
mean  velocity  in  flood  is  between  1.50  and  1.1  meters  per  second.     As 


126 


CHICAGO    METEOROLOGICAL   CONGRESS. 


the  Nile  in  these  reaches  is  in  soil,  it  is  evident  that  a  mean  flood 
velocity  of  1.50  meters  per  second  scours  out  a  channel  whose  width 
is  ninety  times  its  depth,  while  a  velocity  of  over  one  mieter  per  second 
has  a  width  some  fifty  times  its  depth.  The  natural  canals,  which 
take  off  the  river  and  never  silt,  have  a  mean  velocity  of  some  70 
centimeters  per  second  while  the  proportion  of  width  to  depth  is 
about  12  to  1.  Artificial  canals  of  this  section  do  not  silt  if  their 
velocities  are  70  centimeters  per  second,  while  silting  takes  place  as 
readily  when  the  velocity  is  greater  as  when  it  is  less  than  the  above. 
In  muddy  streams,  like  the  Nile  in  flood,  certain  velocities  demand 
certain  proportions  of  width  to  depth,  and  if  these  are  not  given  to 
it  they  will  make  it  for  themselves  by  eating  away  the  sides  if  they 
can,  or  by  silting  up  and  raising  the  bed  if  they  can  not  eat  away  the 
sides. 

On  Rhoda  Island  opposite  Cairo  has  stood  a  gauge  from  very 
ancient  times.  It  has  been  frequently  reconstructed.  The  present 
gauge  was  erected  in  A.  D.  861.  It  is  in  cubits  and  half  cubits  on 
some  very  arbitrary  scale.  When  the  gauge  was  constructed  a  read- 
ing of  16  cubits  on  the  gauge  meant  the  lowest  level  at  which  flood 
irrigation  could  be  insured  everywhere.  In  1887  the  Egyptian  Gov- 
ernment called  upon  all  the  Inspectors  of  Irrigation  to  report  on  the 
minimum  gauge  for  perfect  flood  irrigation,  and  they  reported  20.5 
cubits  on  the  gauge.  The  difference  between  16  and  20.5  cubits  on 
the  Rhoda  Island  gauge  is  1.22  meters,  and  as  1,026  years  had  elapsed 
since  the  construction  of  the  gauge,  it  meant  a  rise  of  0.119  meters 
per  one  hundred  years.  This  is  slightly  undeif  the  rise  calculated  at 
Assu4n,  but  then  the  river  is  muddier  at  Assu^n  than  at  Cairo.  The 
Rhoda  Island  gauge  has  been  read  since  A.  D.  641,  with  interrup- 
tions, and  the  following  table  gives  the  mean  readings  per  century  of 
maximum  flood  and  minimum  low  supply : 


Year  A.  D. 


Flood. 


Low  supply. 


No.  of  years 
recorded. 


641-  700 
700-  800 
800-  900 
900-1000 

lOOO-IIOO 
II00-I2C0 

1200-1300 
1300-1400 
1400-1500 
1500-1600 
1600-1700 
1700- t 800 
1800-1892 


Meters. 
R.  L.,  17.45 
17.44 
17.68 
17.46 
17.62 
17-74 
17.69 
18.17 
18.00 
18.44 
18.81 
19. 12 
20.31 


Meters. 
.  L 


11.48 
10-78 
11.52 
11.30 
II. 61 
12. 17 

11-43 
11.09 
11,81 
11-93 
II. 14 
11.77 
12.71 


62 
100 
100 
100 
100 
100 
100 
100 
52 
52 
28 
94 


The  low-level  gauges  have  been  vitiated  during  the  last  few  years 
by  regulation  at  the  Barrages.  As  the  flood  and  low-level  gauges  in 
the  above  list  have  no  accord  Avith  one  another  they  are  probably 
incorrect,  like  all  other  ancient  records  in  this  country.     Even  in  the 


\ 


THE    NILE.  127 


last  twenty  years  the  flood  gauge  has  been  twice  incorrectly  recorded. 
Napoleon's  savants  relate  how  it  was  incorrectly  recorded  in  1801. 

At  Assu^n  the  Nile  has  a  mean  range  of  7.90  meters  between  high 
and  low  supply,  with  a  maximum  of  9.80  meters  and  a  minimum  of 
6.40  meters.  The  high  supply  varies  between  15,000  and  6,600  cubic 
meters  per  second,  with  a  mean  of  10,300  cubic  meters  per  second, 
while  the  low  supply  varies  between  250  and  1,500  cubic  meters  per 
second,  with  a  mean  of  470  cubic  meters  per  second.  September  is 
generally  the  highest  month  and  May  the  lowest. 

At  Cairo  the  Nile  has  a  mean  range  of  6.70  meters,  with  a  maximum 
of  9.2  meters  and  a  minimum  of  4.90  meters.  The  high  supply  varies 
between  12,500  and  4,900  cubic  meters  per  second,  with  a  mean  of 
7,700  cubic  meters  per  second,  while  the  low  supply  varies  between 
1,300  and  170  cubic  meters  per  second.  October  is  the  highest 
month  and  June  the  lowest. 

The  approximate  areas  of  the  catchment  basins  of  the  Nile  and  its 
tributaries  are  as  follows  : 

Square  kilo- 
meters. 

1.  The  White  Nile  at  the  Ripon  Falls 260,000 

2.  The  White  Nile  between  the  Ripon  and  Fola  Falls 130,000 

S.  The  White  Nile  between  the  Fola  Falls  and  Gondokoro  60,000 

4.  The  White  Nile  between  Gondokoro  and  the  Saubat  Junction...  190,000 

5.  The  Gazelle  River 220,000 

6.  The  Arab  River 340,000 

7.  The  Saubat  River..... 130,000 

8.  The  White  Nile  between  the  Saubat  junction  and  Khartoum 320,000 

9.  The  Blue  Nile 310,000 

10.  The  Atbara  and  Gaash 240,000 

11.  Desert  north  of  Khartoum  910,000 

The  Nile 3,110,000 

If  we  examine  the  plan  and  note  the  length  of  the  different  rivers 
and  their  slope,  it  will  be  evident  that  the  Gazelle,  Saubat,  the  Blue 
Nile,  and  the  Atbara  are  the  ruling  factors  in  flood,  while  the  White 
Nile  is  the  ruling  factor  during  the  remainder  of  the  year. 

The  rainfall  about  Lakes  Victoria  and  Albert,  and  about  Gondokoro 
and  the  upper  halves  of  the  Saubat,  Blue  Nile,  and  Atbara,  may  be 
taken  as  2  meters  per  annum.  In  the  eastern  half  of  the  Gazelle 
River,  the  lower  half  of  the  Saubat,  and  middle  third  of  the  Atbara,  1 
meter  per  annum  may  be  taken  as  the  rainfall.  The  western  half  of 
the  Gazelle  River  has  probably  50  centimeters  per  annum,  while  the 
Arab  River  and  tail  portions  of  the  White  and  Blue  Nile,  and  the 
Atbara,  can  not  have  more  than  25  centimeters  per  annum.  From 
Berber  northward  there  is  a  very  scanty  rainfall  indeed,  and  the 
country  is  considered  rainless.  Applying  these  rainfalls  to  the  catch- 
ment basins  we  obtain  the  total  mean  annual  rainfall  in  the  Nile 
Valley,  as  follows : 


128  CHICAGO    METEOROLOGICAL    CONGEESS. 

Mean  annual  rainfall  in  the  Nile  Valley. 


Square  kil- 
ometers. 

Meters. 

Cubic  meters. 

1. 

260, 000 

X 

1..5 

■=. 

390,  000,  000,  000 

2. 

130,000 

X 

2.0 

rr 

260, 000, 000, 000 

3. 

60, 000 

X 

2.0 

= 

120, 000, 000, 000 

4. 

190,000 

X 

1.5 

z= 

285, 000, 000,  000 

5. 

220, 000 

X 

0.75 

zr 

165,000,000,000 

6. 

340, 000 

X 

0.25 

zz 

85, 000, 000,  000 

7. 

130, 000 

X 

2.00 

= 

260,  000, 000, 000 

8. 

320, 000 

X 

0.  30 

= 

96, 000, 000, 000 

9. 

810, 000 

X 

1.70 

ZZl 

527, 000, 000, 000 

10. 

240, 000 

X 

1.40 

— 

336, 000, 000,  000 

11. 

910,000 

X 

0.12 

= 

109, 000,  000,  000 

3,110,  000  0.  84       2,  633, 000,  000, 000 

We  have  next  to  consider  the  times  of  rainfall.  In  the  great  lake 
regions  the  rainy  season  lasts  from  March  to  December,  with  a  max- 
imum in  August.  At  Gondokoro  the  rains  continue  from  April  to 
November,  with  a  maximum  in  August.  In  the  valley  of  the  Saubat 
tlie  rainy  season  is  from  June  to  Novemljer,  with  a  maximum  in 
August.  It  rains  from  April  to  September  in  the  valley  of  the  Ga- 
zelle River.  From  July  to  September  is  the  rainy  season  at  Khar- 
toum, and  from  July  to  August  in  Kordofan  and  Darfiir,  In  Abys- 
sinia there  are  light  rains  in  January  and  February  and  heavy  rains 
from  the  middle  of  April  to  September,  with  a  maximum  in  August. 
August  is  the  center  of  heavy  rainfall  everywhere. 

The  time  it  takes  the  water  to  travel  down  the  different  lengths  of 
the  river  may  be  found  from  discharge,  velocit}^,  and  slope  calcula- 
tions, and  from  comparisons  between  the  fluctuations  of  the  Gon- 
dokoro, Khartoum,  Assuan,  and  Cairo  gauges.  I  calculate  that  it 
takes  the  water  eight  days  to  travel  from  Lake  Victoria  to  Lake 
Albert  and  five  days  from  Lake  Albert  to  Gondokoro.  There  is  not 
much  difference  between  high  and  low  supply  in  these  reaches.  It 
takes  the  water  thirty-six  days  to  traverse  the  distance  between  Gon- 
dokoro and  Khartoum  in  low  supply  and  twenty  days  in  flood.  Be- 
tween Khartoum  and  Assuan  the  times  are  twenty-six  days  in  low 
supply  and  ten  days  in  flood.  Between  Assuan  and  Cairo  we  have 
twelve  days  in  low  supply  and  six  days  in  flood,  while  between  Cairo 
and  the  sea  we  have  three  days  and  two  days,  respectively.  It  takes 
eighty-four  days  for  the  water  in  low  supply  to  reach  the  sea  from 
Lake  Victoria,  while  in  flood  it  takes  fifty-one  days. 

The  Blue  Nile  traverses  the  distance  between  its  sources  and  Khar- 
toum in  some  seventeen  days  in  low  supply  and  seven  days  in  flood. 
The  Atbara  takes  five  days  in  flood,  and  the  Saubat  can  not  take  a 
much  longer  time. 

Referring  to  the  map  and  keeping  all  the  above  facts  in  mind,  an 
average  year  in  the  Nile  Basin  may  be  thus  described :     The  heavy 


THE    NILE.  129 

rains  near  Gondokoro  begin  in  April  and  force  down  the  green  water 
of  the  swamp  regions.  About  April  15  the  White  Nile  at  Gondokoro 
begins  to  rise,  and  by  September  1  has  reached  its  maximum.  In 
this  interval  the  discharge  has  risen  from  550  cubic  meters  per  second 
to  1,650  cubic  meters  per  second.  This  rise  is  felt  at  Khartoum  about 
May  20,  and  at  Assudn  about  June  10.  The  green  water  announcing 
this  rise  is  seen  at  Cairo  about  June  22.  In  an  average  year  on  May 
20,  the  White  Nile  discharge  of  300  cubic  meters  per  second  at  Khar- 
toum begins  to  increase,  and  goes  on  gradually  increasing  to  Septem- 
ber 15  or  20,  when  the  maximum  floods  of  the  White  Nile  and  Saubat 
reach  Khartoum  and  attain  a  discharge  of  5,000  cubic  meters  per 
second.  The  low-water  discharge  of  the  Blue  Nile  is  160  cubic  meters 
per  second,  and  about  June  5  it  begins  to  rise  fairly  quickly  and 
reaches  its  ordinary  maximum  of  5,000  cubic  meters  per  second  by 
about  August  25.  Owing  to  the  two  floods  rarely  being  contemporary 
the  ordinary  maximum  flood  of  8,000  cubic  meters  per  second  is  gen- 
erally on  September  5.  The  red,  muddy  water  of  the  Blue  Nile  reaches 
Assuan  about  July  15,  and  Cairo  about  July  25.  Once  the  red  water 
begins  to  appear  the  rise  is  rapid,  for  the  Atbara  is  in  flood  shortly 
after  the  Blue  Nile,  and  its  flood  waters  rise  with  great  rapidity.  The 
Atbara  would  come  down  much  earlier  than  it  does  were  it  not  that 
a  whole  month  is  expended  in  saturating  the  desert  and  its  own  dry 
sandy  bed.  The  Atbara  flood  begins  in  the  early  part  of  July  and  is 
at  its  highest  about  August  20,  reaching  an  ordinary  maximum  of 
3,400  cubic  meters  per  second,  and  occasionally  an  extraordinary 
maximum  of  4,900  cubic  meters  per  second. 

It  is  owing  to  the  earliness  of  the  Atbara  high  flood  and  the  lateness 
of  the  White  Nile  high  flood  that  the  ordinary  maximum  discharge 
of.  the  Nile  at  Assuan  is  only  10,300  cubic  meters  per  second.  This 
is  generally  on  September  5.  When  the  White  Nile  is  weak  the  max- 
imum at  Assuan  is  reached  before  or  on  September  5 ;  when  the 
White  Nile  is  strong  the  maximum  is  reached  about  September  20. 
An  early  maximum  at  Assuan  is  always  followed  by  a  low  summer 
supply,  while  a  late  maximum  is  nearly  always  followed  by  a  high 
summer  supply.  Only  once  has  this  rule  been  broken  and  that  was 
in  1891,  when  there  were  two  maximums,  one  on  September  4  and 
another  on  the  27th.  In  this  year  there  must  have  been  an  extra- 
ordinary fall  of  rain  in  Abyssinia  in  September,  for  the  flood  of  Sep- 
tember 27  was  very  muddy,  while  as  a  rule  the  river  at  Assuan  is  very 
muddy  in  August,  less  so  in  September,  and  very  much  less  so  in 
October,  when  the  White  Nile  is  the  ruling  factor  in  the  supply  of 
the  river. 

Appendix  I  contains  discharge  tables  of  the  Khartoum,  A88uS.n, 
and  Cairo  gauges.  The  zero  is  everywhere  mean  low-water  level. 
Appendix  II  gives  five  daily  gauges  and  discharges  of  the  Nile  at 
9 


130  CHICAGO    METEOROLOGICAL    CONGEESS. 

Khartoum  during  flood.  Appendix  III  gives  five  daily  gauges  and 
discharges  of  the  Nile  at  Assu^n  throughout  the  year.  Appendix  IV 
gives  five  daily  gauges  and  discharges  of  the  Nile  at  Cairo. 

If  the  White  Nile  happens  to  be  in  very  heavy  flood  late  in  Sep- 
tember, and  the  September  rains  in  Abyssinia  are  also  very  heavy, 
an  extraordinary  flood  passes  Assu^n  at  the  end  of  September  and  is 
disastrous  for  Egypt.  This  happened  in  1878.  Appendices  III  and 
IV  contain  details  of  this  flood,  of  the  minimum  flood-year,  1877, 
and  the  mean  of  the  twenty  years  from  1873  to  1892. 

At  Assu^n  the  Nile  enters  Egypt,  and  it  now  remains  to  consider 
it  in  its  last  1,200  kilometers.  The  ordinary  minimum  discharge  at 
AssuAn  is  170  cubic  meters  per  second,  and  is  reached  about  the  end 
of  May.  The  river  rises  slowly  till  about  July  20,  and  then  rapidly 
through  August,  reaching  its  maximum  about  September  5,  and  then 
falling  very  slowly  through  October  and  November.  The  tables  in 
Appendix  III  give  every  detail  of  a  maximum,  minimum,  and  mean 
year.  The  deep  perennial  irrigation  canals  take  water  all  the  year 
round,  but  the  flood  irrigation  canals  are  closed  with  earthern  banks 
till  August  15,  and  are  then  all  opened.  These  flood  canals,  of  which 
there  are  some  forty-five,  are  capable  of  discharging  2,000  cubic  meters 
per  second  in  an  ordinary  year,  and  have  an  immediate  effect  on  the  dis- 
charge of  the  Nile.  The  channel  of  the  Nile  itself  and  its  numerous 
branches  and  arms  consume  a  considerable  quantity  of  water ;  the 
perennial  canals  take  200  cubic  meters  per  second,  the  direct  irriga- 
tion from  the  Nile  between  Assu^n  and  Cairo  takes  100  cubic  meters 
per  second,  and  100  cubic  meters  per  second  are  lost  by  evaporation 
off  the  Nile.  Owing  to  all  these  different  causes  there  is  the  net 
result  that  from  August  15  to  October  1  the  Nile  is  discharging  2,800 
cubic  meters  per  second  less  at  Cairo  than  at  Assu^n.  During  Octo- 
ber and  November  the  flood  canals  are  closed,  and  the  basins  which 
have  been  filled  in  August  and  September  discharge  back  into  the 
Nile,  and  from  October  5  to  November  15  the  Nile  at  Cairo  is  dis- 
charging 1,000  cubic  meters  per  second  in  excess  of  the  discharge  at 
Assu^n.  An  examination  of  Appendices  III  and  IV  will  show  this 
very  clearly. 

The  ordinary  minimum  discharge  at  Cairo  is  370  cubic  meters  per 
second,  and  is  attained  on  June  10 ;  the  river  rises  slowly  through 
July,  and  fairly  quickly  in  August,  and  reaches  its  ordinary  maximum 
on  October  1,  when  there  is  no  irrigation  in  the  basins  and  the  dis- 
charge from  the  basins  is  just  beginning.  The  ordinary  maximum 
discharge  at  Cairo  is  about  7,700  cubic  meters  per  second.  Through 
October  the  Nile  at  Cairo  is  practically  stationary,  and  falls  rapidly 
in  November. 

North  of  Cairo  are  the  heads  of  the  perennial  canals  which  irrigate 
the  Delta  proper.     These  canals,  with  their  feeders  lower  down,  dis- 


THE    NILE.  131 

charge  1,200  cubic  meters  per*  second,  and  the  ordinary  maximum 
flood  at  Cairo  of  7,700  cubic  meters  per  second  is  reduced  by  this 
amount  between  Cairo  and  the  sea.  Of  the  6,500  cubic  meters  per 
second  which  remain,  4,200  cubic  meters  per  second  find  their  way  to 
the  sea  down  the  Rosetta  branch  and  2,300  cubic  meters  per  second 
down  the  Damietta  branch.  During  extraordinary  floods  the  Dami- 
etta  branch  has  discharged  4,300  cubic  meters  per  second  and  the 
Rosetta  branch  7,000  cubic  meters  per  second. 

We  have  so  far  considered  the  Nile  in  flood,  it  now  remains  to 
quickly  dispose  of  the  low  supply.  After  reaching  its  maximum,  the 
Atbara,  which  is  a  torrential  river,  falls  more  rapidly  than  the  others, 
and  by  the  end  of  October  has  practically  disappeared.  After  the 
middle  of  September  the  Blue  Nile  falls  quickly,  while  the  White 
Nile,  with  its  large  basin,  gentle  flow,  and  numerous  reservoirs,  falls 
very  deliberately.  The  mean  discharge  of  the  White  Nile  at  Gon- 
dokoro,  in  an  ordinary  year,  at  the  time  of  low  supply,  is  550  cubic 
meters  per  second.  By  the  time  it  reaches  Khartoum  it  is  reduced 
by  evaporation  to  some  350  cubic  meters  per  second.  The  ordinary 
low  supply  of  the  Blue  Nile  is  190  cubic  meters  per  second,  giving  an 
ordinary  low  supply  to  the  Nile  at  Khartoum  of  540  cubic  meters  per 
second.  The  Atbara  supplies  nothing.  Between  Khartoum  and 
Assu^n  there  is  a  further  loss  from  evaporation  and  irrigation  of  70 
cubic  meters  per  second,  and  the  ordinary  low  supply  delivered  at 
Assu^n  is  470  cubic  meters  per  second.  In  very  bad  years  the  dis- 
charge at  Assu4n  has  fallen  to  240  cubic  meters  per  second,  which 
would  mean  310  cubic  meters  per  second  at  Khartoum,  probably; 
and,  adopting  Linant  Pasha's  proportion,  the  White  Nile  would  be 
discharging  200  cubic  meters  per  second  and  the  Blue  Nile  110  cubic 
meters  per  second.  As  the  White  Nile  at  Gondokoro  never  discharges 
much  under  500  cubic  meters  per  second,  the  loss  on  that  river,  under 
the  most  unfavorable  conditions,  is  about  300  cubic  meters  per  second, 
while  the  loss  on  the  Blue  Nile  cannot  be  more  than  50  cubic  meters 
per  second.  Summing  up,  therefore,  we  may  state  that  in  a  very  bad 
summer  the  Nile  sources  supply  660  cubic  meters  per  second,  the  dis- 
charge at  Khartoum  has  dwindled  to  310  cubic  meters  per  second 
and  at  As8u4n  to  240  cubic  meters  per  second.  The  moment  the 
daily  fall  of  the  river  becomes  less  than  the  daily  loss  by  evaporation 
all  the  small  ponds  and  pools  cease  to  aid  the  stream,  and  if  they  are 
very  extensive,  as  they  are  south  of  Fashoda,  they  diminish  the  dis- 
charge considerably  by  their  large  evaporating  areas.  The  six  cata- 
racts of  the  Nile,  with  their  numerous  raised  sills,  moderate  the  floods 
and  lengthen  them  out,  but  when  the  two  months  of  real  low  dis- 
charge have  come  the  great  reservoirs  of  the  Nile  are  the  sole  sources 
of  supply. 

As  Egypt  possesses   no  barometric,  thermometric,  or  rain-gauge 


132  CHICAGO    METEOROLOGICAL   CONGRESS. 

stations  in  the  valley  of  the  Nile,  we  are  always  ignorant  of  the  com- 
ing flood,  though  famine  years  in  India  are  generally  years  of  low 
flood  in  Egypt.  If,  however,  the  summer  supply  of  the  Nile  has  been 
exceedingly  low  and  exceedingly  late,  we  anticipate  a  high  flood  fol- 
lowing it,  as  the  drought  in  the  valley  of  the  White  Nile  must  create 
a  powerful  draught  on  to  the  Indian  Ocean.  Again,  as  to  the  summer 
supply,  we  generally  anticipate  a  poor  volume  in  the  river  at  that 
season  if  the  Nile  flood  at  Assu&n  is  an  early  one,  and  a  good  sup- 
ply if  the  Nile  flood  at  Assu^n  is  a  late  one.  Appendix  V,  which 
contains  numerous  statistics  of  times  and  proportions  of  flood  and 
low  supply  for  the  twenty  years  from  1873  to  1892,  fully  bears  out 
this  statement.  Between  Assudn  and  Cairo,  previous  to  1890,  we  had 
little  control  over  the  flood,  as  the  canals  and  escapes  in  upper  Egypt 
had  no  masonry-regulating  works,  and  the  Nile  in  high  flood  did  very 
much  what  it  liked.  Since  1890,  however,  the  Public  Works  Depart- 
ment has  constructed  ninety  important  regulating  works,  and  by 
proper  manipulation  we  can  now  fairly  control  a  high  flood  by  using 
the  canals  and  escapes  so  as  not  to  let  the  Nile  at  Cairo  rise  above  8 
meters,  which  is  the  maximum  gauge  the  banks  on  the  Rosetta  and 
Damietta  branches  can  support  with  any  degree  of  security.  It  was 
mainly  owing  to  this  power  of  control  that  the  excessive  flood  of  1892 
passed  through  Egypt  without  causing  any  real  damage.  The  Egyp- 
tian Government  to-day  is  very  seriously  considering  the  question 
of  flood  control  and  increase  of  summer  supply,  and  we  hope  to  find 
a  solution  for  the  former  by  escaping  excess  flood  water  into  some  of 
the  depressions  which  border  the  Nile  Valley,  and  a  solution  for  the 
latter  by  the  creation  of  reservoirs  either  in  the  deserts  and  the  chan- 
nel of  the  Nile  itself  north  of  Wady  Haifa,  or  by  regulating  works  at 
the  sources  of  the  rivers  themselves,  or  perhaps  by  a  combination  of 
both. 

When  we  consider  the  energy  and  the  self-denying  labors  of  the 
men  who  achieved  the  great  discoveries  of  the  sources  of  the  Nile,  it 
seems  but  a  poor  compensation  to  them  to  know  that  these  sources 
can  now  be  depicted  on  the  plans.  It  would  be  a  triumph  indeed,  and 
a  real  compensation,  if  the  resources  of  modern  science  could  be  em- 
ployed to  utilize  these  great  lakes,  and  by  the  construction  of  suitable 
works  to  insure  a  constant  and  plentiful  supply  of  water  to  the  Nile 
Valley  during  the  summer  months  when  water  is  scarce  and  as  valu- 
able as  gold.  Both  the  Victoria  and  the  Albert  lakes  lend  themselves 
to  be  utilized  as  reservoirs  as  they  have  rocky  sills  at  their  outlets, 
while  the  Albert  and  Tsana  lakes,  by  their  convenient  size,  are  emi- 
nently suited  for  regulating  basins.  The  day  these  works  are  carried 
out  at  the  sources  of  the  Nile  the  lakes  will  take  their  proper  place 
in  the  economy  of  the  water  supply,  and  we  shall  be  able  to  say  of 
them  in  their  entirety,  as  we  can  say  of  them  to-day  in  their  degree, 


K 


>lf 


-     s  ^ 


f^: 


JJT.  ATsT   OF  TTT"*^  NHjE,    ftoin   JujstuB  Pertbe's  .AS^ico..      Berlizi,  l&Oa. 


I 


I 


THE    NILE. 


133 


that  what  the  snows  of  the  Alps  are  to  the  Po,  lakes  Victoria,  Nyanza, 
and  Tsana  are  to  the  Nile,  and  what  the  Italian  lakes  are  to  the  plains 
of  Lombardy,  Lake  Albert  is  to  the  land  of  Egypt. 

APPENDICES. 

I. — Discharge  Tables  for  the  Khartoum,  Assuan,  and  Cairo 

Gauges. 

The  discharges  opposite  the  gauges  are  mean  discharges.  On  a 
rising  Nile  the  discharges  are  in  excess  of  those  in  the  table,  and  on 
a  falling  Nile  they  are  under  them.  This  will  be  noticed  in  Appen- 
dices III  and  IV. 

The  site  chosen  for  taking  the  discharges  of  a  river  throughout  the 
year  should  be  such  that  the  bed  of  the  river  at  the  site  would  be  dry 
if  the  discharge  fell  to  zero.  Deep,  scoured-out  sections  of  a  river 
may  give  fairly  accurate  discharges  in  high  flood,  but  they  give  very 
inaccurate  discharges  in  low  supply,  as  the  action  which  causes  the 
scour  exists  only  in  flood. 

The  following  discharges  have  been  calculated  from  observed  sur- 
face velocities  on  Harlacher's  method  (using  0.85  as  the  reducing 
constant),  and  from  Manning's  formula  and  surface  slope  observa- 
tions (using  33  as  the  constant) : 

Approximate  discharge  table  for  the  Khartoum  gauge. 

[The  zero  of  the  gauge  is  mean  low-water  level  or  R.  L.  384.00,  or  6.30  meters  on  the  gauge  which 
used  to  stand  in  front  of  old  Government  house  at  Khartoum.  Gauges  in  meters ;  discharges  in 
cubic  meters  per  second.] 


Gauge. 

1 
Discharge.        Gau 

ge.       Discharge.        Gau 

ge. 

Discharge.        Gau 

ge. 

Discharge. 

I.S 

1, 460                 3 

1 

2,700                   4 

7 

4,000           1        6 

3 

7,420 

6 

1.530 

2 

2,750 

8 

4,180 

4 

7.690 

7 

1,600 

^ 

2,800 

9 

4.360 

5 

7,960 

8 

1,690 

4 

2, 850                   5 

0 

4.540 

6 

8,230 

P 

1,780         , 

5 

2,900 

I 

4,720 

7 

8,500 

2 

0 

1,870 

6 

2,950 

2 

4,900 

8 

8,900 

1 

1,960 

7 

3,000 

3 

5.080 

9 

9.300 

2 

2,050 

8 

3,100 

4 

5.260                  7 

0 

9,700 

w 

3 

2,140 

9 

3.200 

5 

5.440 

I 

10, 100 

M- 

4 

2, 230                 4 

0 

3.300 

6 

5,620 

2 

10,500 

W' 

S 

2,320 

I 

3.400 

7 

5,800 

3 

10,900 

6 

2,410 

2 

3.500 

8 

6,070 

4 

11,300 

7 

2,500 

3 

3,600 

9 

6,340 

5 

11,700 

g 

2i550 

4 

3,700                  6 

0 

6,610 

6 

12,100 

9 

2,600 

3,800 

I 

6,880 

7 

12,500 

3 

0 

2,650 

"" 

3.900 

a 

7.150 

8 

12,900 

Discharge  table  for  the  Assuan  gauge. 

[Zero  on  the  gauge  is  mean  low-water  level  or  R.  L.  85.00.    Gauges  in  meters;  discharges  in  cubic 

meters  per  second.] 


Gauge. 

Discharge. 

Gauge. 

Discharge. 

Gauge. 

Discharge. 

Gauge. 

Discharge. 

— 2.00 

0 

—1.20 

no 

—  .40 

330 

0.40  • 

650 

—1.90 

5 

—1. 10 

130 

-  .30 

360 

•50 

700 

—I. So 

10 

— 1. 00 

'50 

—  .20 

400 

.60 

750 

—1.70 

20 

—  .90 

180 

—  .  10 

440 

•70 

800 

—1.60 

30 

—  .80 

210 

0.00 

470 

.80 

850 

—1.50 

50 

—  .70 

240 

.10 

510 

0.90 

900 

—1.40 

70 

—  .60 

270 

.20 

550 

950 

—1.30. 

90 

-  -50 

300 

.30 

600 

.  10 

1,010 

134 


CHICAGO    METEOROLOGICAL    CONGRESS. 

Discharge  table  for  the  Assudn  gauge — Continued. 


Gauge. 

Discharge. 

Gauge. 

Discharge. 

Gauge. 

Discharge. 

Gauge. 

Discharge. 

1.20 

1,070 

3-30 

2,610 

5-40 

4.860 

7-50 

9,000 

•3° 

1,130 

.40 

2,700 

•50 

5.000 

•  60 

9.320 

.40 

1,190 

•50 

2.790 

.60 

5.140 

.70 

9,640 

•50 

1.250 

.60 

2,880 

.70 

5,280 

.80 

9,960 

.60 

1.310 

.70 

2,970 

.80 

5.420 

.90 

10,280 

.70 

1.370 

.80 

3,060 

.90 

5.560 

8.00 

10, 600 

.80 

1.430 

.90 

3.150 

6.00 

5,800 

.10 

11,020 

.90 

1,490 

4.00 

3.240 

.  10 

6,000 

.20 

11,440 

2.00 

1.550 

.10 

3.356 

.20 

6,  200 

1        -30 

11,860 

.10 

1,610 

.20 

3.472 

•30 

6,400 

.40 

12, 280 

.20 

1,670 

•30 

3.588 

.40 

6,600 

•50 

12,700 

•30 

1.750 

.40 

3.704 

•50 

6,800 

.60 

13, 120 

.40 

1,830 

•  50 

3.820 

.60 

7,000 

.70 

13.540 

•50 

1,910 

.60 

3.936 

•70 

7,200 

.80 

13.960 

.60 

1,990 

.70 

4.052 

.80 

7.400 

.90 

14, 380 

.70 

2,070 

.80 

4,168 

.90 

7,600 

9.00 

14,800 

.80 

2, 160 

.90 

4.284 

7.00 

7,800 

.10 

15, 22c 

.90 

2,250 

5-00 

4,400 

.10 

8,040 

■  20 

15.640 

3.00 

2,340 

.10 

4.540 

.20 

8,280 

.  10 

2,430 

.20 

4,680 

•30 

8, 520 

.20 

2,520 

•30 

4,720 

.40 

8, 760 

Discharge  table  for  the  Cairo  gauge. 

[Gauges  in  meters.  Discharge  in  cubic  meters  per  second.  Zero  on  the  gauge  is  mean  low- 
water  level  or  R.  L.  12.70.  Regulation  at  the  Barrages  vitiates  the  discharges  below  1.60  at  the 
present  time.] 


Gauge. 

Discharge. 

Gauge. 

Discharge.        Ga 

age. 

Discharge. 

Gauge. 

Discharge. 

— 1.20 

0 

1.30 

1,300                      3 

80 

3.750 

6.30 

6,800 

—1. 10 

15 

.40 

1,290 

90 

3,860 

.40 

7.050 

— 1. 00 

30 

•50 

1. 380        :      4 

00 

3.970 

•50 

7.300 

—  .90 

60 

.60 

1.470         n 

10 

4,080 

.60 

7.550 

-  .80 

90 

•70 

1.560 

20 

4,190 

•70 

7,800 

—  .70 

120 

.80 

1,650         1 

,•^0 

4.300 

.80 

8,050 

-  .60 

150 

.90 

1,740         '1 

40 

4,410 

.90 

8,300 

—  .50 

180 

2. 00 

1.830         :; 

.■io 

4.520 

7.00 

8,550 

—  .40 

220 

•  10 

1.920         ii 

60 

4,630 

.10 

8,800 

—  .30 

260 

.20 

2,010         1' 

70 

4,740 

.20 

9.050 

—  .20 

300 

•30 

2, 100         11 

80 

4,850 

•30 

9.300 

—  .10 

340 

.40 

2,210         1 

90 

4,960 

.40 

9.570 

0.00 

380 

•50 

2, 320               5 

00 

5.070 

•50 

9,840 

.  10 

420 

.60 

2,430 

10 

5,180 

.60 

10,  no 

.20 

460 

.70 

2,540 

20 

5.290 

•70 

10, 380 

•30 

500 

.80 

2,650 

30 

5.400 

.80 

10,650 

.40 

570 

.90 

2,760         ,1 

40 

5.540 

.90 

10, 920 

.50 

640 

3.00 

2, 870 

50 

5,680 

8.00 

II,  190 

.60 

710 

.10 

2.9S0          1 

60 

5.820 

.  10 

11,460 

•70 

780 

■  20 

3.090         ! 

70 

5,960 

.20 

11,730 

.80 

850 

•30 

3.200        j 

80 

6, 100 

•30 

12,000 

.90 

920 

.40 

3. 310          1 

90 

6,240 

.40 

12,270 

1. 00 

990 

•50 

3, 420             ;         6 

00 

6,380 

..so 

12,540 

.10 

1,060 

.60 

3.530 

ID 

6, 520 

.60 

12,8X0 

.20 

1.130 

.70 

3.640 

1 

20 

j          6,660 

1 

II. — Khaetoum. 


Five  daily  gauges  and  discharges  for  the  maximum,  minimum,  and 
mean  years,  from  1873  to  1882,  during  flood. 

Zero  on  the  gauge  is  mean  low-water  level,  R.  L.  384.00  meters,  or 
6.80  meters  on  the  old  gauge  at  Khartoum,  on  the  Blue  Nile. 


THE    NILE. 


136 


Gauges  in  meters  and  discharges  in  cubic  meters  per  second  of  the  Nile  at  Khartoum 

for  the  maximum,  minimum,  and  mean  years  between  1873  and  1882. 

[Zero  on  the  gauge  is  mean  low-water  level.] 


Date. 


Maximum,  1878. 


Gauge.      Discharge. 


Minimum,  1877. 


Gauge.      Discharge. 


Mean  of  10  years. 


Gauge.      Discharge. 


June  15 

20 

25 

July     I 

5 

10 

15 

20 

25 

Aug.      1 

5 

10 

15 

20 

25 

Sept.    I 

5 

10 

15 

20 

25 

Oct.      I 

5 

10 

15 

June  15  to  July  15 

July  15  to  August  15 

August  15  to  September  15  . 
September  15  to  October  15. 


2. 00 
2.00 

2-45 
2.80 
2.80 
3.20 
3-70 
4-3° 
4-40 
4.60 
5.60 
6.05 
6.40 
6.20 
6. 10 
6.80 
7.10 
7-3° 
7  ..so 
7.80 
7.60 
7.40 
7-05 
6-75 
6.40 
2.70 
5.00 
6-75 
7-25 


1,870 
1,870 
2,320 
2.550 
2,550 
2.750 
3.000 
3,600 
3.700 
3.900 
5,620 
6,880 
7,690 
7.150 
6,880 
8,900 
10, 100 
10, 900 
11,700 
12,900 
12, 100 
11,300 
9.700 
8,500 
7,690 
2,410 
4,840 
8,940 
10, 700 


1.90 
2. 10 
2-45 
3-00 
2.90 
3-55 
3- 80 
4-30 
4-30 
4-95 
4.60 
5.20 

5-15 
5. 10 
5. 35 
5.20 
5-10 
5-20 
5-30 

5-20 

4-95 
4-50 
4.40 
4.20 
4.10 
2.80 
4-65 
5.20 
4-65 


1,780 
1,960 
2,320 
2,650 
2,600 
2.950 
3,100 
3,600 
3,600 
4.360 
3,900 
4,900 
4,800 
4,720 
5,150 
4,900 
4,720 
4,900 
5,080 
4,900 
4,360 
3,800 
3.700 
3.500 
3.400 
2,490 
4,050 
4,890 
4,080 


1.70 
1.85 
2.25 
2.6s 
2.85 
3-30 
3- 60 
4. 10 
4.60 
5-25 
5- 60 
5-95 
6.15 
6.15 
6.35 
6.50 
6.45 
6.S& 
6.50 
6.50 
6.30 
5-90 
5-70 
5-50 
5-15 
2.60 
5.10 
6.40 
5-90 


1,600 
1,780 
2, 140 
2,500 
2,600 
2,800 
2,950 
3.400 
3.900 
5,080 
5,620 
6,610 
7,000 
7,150 
7,600 
7,960 
7,800 
8, 100 
7,960 
7,960 
7,420 
6,340 
5,800 
5.440 
4,720 
2,350 
4.930 
7,680 
6,550 


III. — ASSUAN. 

Five  daily  gauges  and  discharges  for  the  maximum,  minimum,  and 
mean  years  from  1873  to  1892. 

Mean  monthly  and  yearly  discharges  for  the  maximum,  minimum, 
and  mean  years  from  1873  to  1892. 

Zero  on  the  gauge  is  mean  low-water  level,  i.  e.,  R.  L.  85.00  meters 
above  sea  level. 

Gauges  in  meters  and  discharges  in  cubic  meters  per  second  for  the  maximum,  mini- 

mtim,  and  mean  years  between  1873  and  1892. 

[Zero  on  the  gauge  is  mean  low-water  level.] 


Date. 


June    I 

5 
10 
15 
20 

25 
July     I 

5 
10 

15 
20 

^5 
Aug.     I 

5 


Maximum,  i878-'79. 


Gauge.       Discharge. 


-  .68 

-  .66 

-  -59 

-  -32 
.67 
•94 

1.05 
1.44 
2.47 
3.82 
5-39 
5-62 
6.25 


240 

.19 

240 

.28 

240 

.46 

240 

.91 

270 

1.09 

360 

1.07 

800 

1.30 

950 

1. 81 

1,010 

2.13 

1,250 

3-23 

1,910 

3-23 

3,150 

3-70 

4,860 

4.72 

5.280 

4.78 

6,400 

5-35 

Minimum,  i877-'78. 


Gauge.       Discharge. 


Mean  of  20  years. 


Gauge.       Discharge. 


550 

.06 

480 

600 

.  10 

510 

700 

.  10 

510 

900 

•36 

650 

1,010 

•49 

700 

1,000 

•72 

850 

1,130 

1. 12 

1,010 

1,490 

1^39 

1, 190 

1.670 

1.82 

1,450 

2,610 

2.25 

1,700 

2,610 

2.87 

2,250 

2,970 

3^71 

3,060 

4,170 

5-16 

4,680 

4,170 

5-71 

5,420 

4,860 

6.59 

7,000 

136  CHICAGO    METEOROLOGICAL   CONGRESS. 

Gauges  in  meters  and  discharges  in  cubic  meters  per  second,  etc. — Continued. 


Date. 


Maximum,  i878-'79.         Minimum,  1877- '78 


Gauge.       Discharge.   {  Gauge.       Discharge. 


Mean  of  20  years. 


Gauge.       Discharge. 


Aug. 
Sept. 


25- 


25- 


Nov. 


Dec.      I. 


Jan. 


Feb.      I . 


April 


May 


Month. 


June  

July 

August 

September 
October.... 
November. 
December  . 
January  . . . 
February  . . 

March 

April 

May 


Mean  of  the  year 


7.17 
7.48 
8.07 
7.60 
8.14 
8.52 
8.90 
8.86 
9.00 
9.15 
8.92 

8.47 
7.91 
7.60 
7.42 
6.72 

6-34 
5-86 
5-50 
5-17 
4.92 
4.67 
4-54 
4-38 
4.20 
4.09 
3-93 
3-7° 
3-59 
3-52 
3-41 
3-28 
3.20 
3.12 
3-05 
2.96 
2.89 
2-83 
2.78 
2.74 
2.71 
2.67 
2.60 
2.58 
2.51 
2.44 
2.38 
2.31 
2.22 
2.17 
2.26 
2.24 
2.20 

2.02 

1-95 
1.90 
2.00 
2-17 


-  -49 

2.12 
6.85 
8.63 
8.04 

5-58 

4-22 

3-40 
2.91 
2.61 
2. 28 
2.04 

4.02 


8,280 
9,000 
11,020 
9>320 
11,440 
13, 120 
14, 380 
131960 
14, 800 
15, 220 
14, 380 
12,280 
10,  280 
9>320 
8,760 

7,200 

6,400 
5. 420 
Siooo 
4.540 
4,280 
3.940 
3.820 
3.590 
3.470 
3.360 
3.150 
2.970 
2,880 
2,790 
2,700 
2,520 
2,520 
2.430 
2,340 
2,250 
2, 160 
2, 160 
2,070 
2,070 
2,070 
1,990 
1,990 
1,910 
1,910 
1,830 
1, 800 
1.750 
1,670 
1,650 
1,700 
1,700 
1,670 
1. 550 
1,490 
1,490 
1.550 
1,670 


320 
1,850 
7.840 
13. 330 
11,040 
5.120 
3. 470, 
2,680 
2,200 
1,970 
1,720 
1,580 

4.430 


•76 
2.85 
5-64 

6.J2 

4.98 
3-36 
2.25 
1.62 
.80 
.16 

-  .24 

-  -51 
2.32 


5.420 

7 

04 

6,600 

7 

34 

6,000 

7 

62 

6,200 

? 

8S 

6,300 

9S 

5,800 

7 

92 

5,800 

7 

87 

5.560 

7 

72 

6,400 

7 

62 

5,800 

7 

30 

5.140 

7 

00 

4,680 

6 

65 

4,280 

6 

32 

3.940 

,S 

98 

3,820 

5 

65 

3,060 

5 

II 

2,970 

4 

83 

2,880 

4 

51 

2,700 

4 

23 

2,520 

4 

00 

2,250 

3 

76 

1,990 

3 

51 

1,910 

3 

.38 

1,830 

.S 

24 

1,670 

3 

08 

1,610 

2 

96 

1,490 

2 

85 

1,490 

2 

64 

1,490 

2 

55 

1,370 

2 

45 

1,310 

2 

33 

1, 190 

2 

22 

1. 130 

2 

II 

1,070 

95 

950 

86 

900 

74 

850 

61 

800 

48 

700 

39 

650 

28 

600  ■ 

19 

550 

08 

520 

98 

500 

87 

47P 

76 

440 

61 

400 

.53 

400 

44 

360 

37 

360 

31 

330 

26 

330 

18 

300 

15 

300 

09 

300 

08 

270 

04 

270 

0 

00 

260 

■05 

840 

•39 

1,670 

2-53 

5,370 

6.80 

5.940 

7-77 

4,420 

6.30 

2,640 

4-37 

1,710 

3.10 

1,280 

2-33 

840 

1.62 

530 

•97 

380 

•39 

290 

08 

2, 160 


3-05 


THE    NILE. 


137 


IV. — Cairo. 

Five  daily  gauges  and  discharges  for  the  maximum,  minimum,  and 
mean  years  between  1873  and  1892. 

Mean  monthly  and  yearly  discharges  for  the  maximum,  minimum, 
and  mean  years  from  1873  to  1892. 

Zero  on  the  gauge  is  mean  low-water  level,  i.  e.,  R.  L,  12.70  meters 
above  sea  level. 

Gauges  in  meters  and  discharges  in  cubic  meters  per  second  for  the  maximum,  mini- 
mum, and  mean  years  betiveen  1873  and  1892. 
[Zero  on  the  gauge  is  mean  low-water  level.] 


Date. 


Maximum,  1878- '79. 


Gauge.      Discbarge.   |   Gauge.   '  Discharge. 


Minimum,  i877-'78. 


Mean  of  20  years. 


Gauge.      Discharge. 


15 
20 

25 
July    I 

5 

ID 
15 
20 

25 
Aug.      I 

5 
10 

15 
20 

25 
Sept.    I 

5 
10 
15 
20 

^3 
Oct.      I 

5 
10 

15 
20 

25 
Nov.     1 

5 
10 

15 
20 

^5 
Dec.     I 

5 
10 

15 
20 

Jan.      I 

5 
10 

15 
20 

25 
Feb.     I 

5 
10 

15 
20 

25 

Mar.     I 

10 

15 
20 

25 


-  .42 

180 

28 

-  .48 

180 

17 

-  -55 

180 

15 

-  -57 

170 

17 

-  .62 

170 

21 

-  .6g 

170 

48 

-  .64 

170 

73 

-  .60 

170 

70 

-  .10 

300 

75 

•33 

500 

90 

•52 

600 

I 

12 

•97 

950 

I 

91 

2-54 

2,430 

2 

.S8 

3-66 

3,640 

3 

19 

4.40 

4,410 

3 

75 

4.90 

4,960 

4 

08 

5-73 

6, 100 

4 

15 

V8S 

6,240 

i 

it 

6.16 

6,660 

4 

81 

6.08 

6,380 

4 

78 

6.38 

7.050 

4 

«3 

6.72 

8,050 

4 

75 

7-23 

9,100 

4 

74 

7-52 

10,000 

4 

63 

7-98 

II,  190 

4 

80 

8.07 

11,460 

4 

74 

8-54 

12,540 

4 

59 

8.2,S 

11.730 

4 

40 

8.11 

11,460 

4 

II 

7.80 

10, 650 

3 

91 

7-33 

9.300 

3 

68 

7.10 

8,800 

3 

43 

6.96 

8,300 

3 

15 

6.45 

7.050 

3 

2b 

5-7° 

5.960 

3 

21 

5.06 

5.070 

3 

02 

4-63 

4.630 

2 

04 

4-45 

4,410 

2 

48 

4.24 

4,190 

2 

26 

4.04 

3.970 

2 

15 

3-91 

3.860 

2 

03 

3-79 

3.700 

91 

3-5° 

3.420 

82 

3-35 

3,200 

75 

3-19 

3,000 

69 

2.96 

2,890 

60 

2.91 

2,760 

40 

2.S1 

2,650 

33 

2.68 

2.450 

20 

2.64 

2.450 

12 

2.S6 

2,400 

01 

2.46 

2,210 

88 

2.40 

2,210 

75 

2.34 

2, 100 

66 

2. -52 

2,100 

59 

2.28 

2,010 

52 

2.21 

2,010 

44 

2.17 

1,920 

46 

2.13 

1.920 

50 

2.09 

i>8so 

39 

450 
430 
430 
430 
440 

600 
700 
700 
800 
900 

1,010 

1.830 

2,210 

3.090 

3.760 

4,080 

4,190 

4,900 

4.850 

4.740 

4.850 

4,800 

4,800 

4.630 

4.850 

4.740 

4.520 

4.410 

4,000 

3.860 

3.530 

3.310 

2,980 

3.090 

3.090 

2,870 

2.430 

2,210 

2,010 

1,920 

1,830 

1,740 

1,650 

1,560 

1,470 

1.470 

1,290 

1,200 

1.130 

1,060 

990 

850 

780 

710 

640 

640 

570 

500 

470 

420 


380 

370 

370 

370 

420 

420 

500 

550 

700 

900 

1,200 

1,700 

2.430 

3.640 

4.520 

5.400 

5.680 

5.960 

6,038 

6,520 

6,800 

7.050 

7.300 

7.550 

7.650 

7.300 

7, 100 
7.050 
6,800 
6,660 
5.820 
5,200 
4.630 
4,190 
3.750 
3.420 
3,200 
3,000 
2,800 
2,650 
2.540 
2,400 
2,210 
2,150 
2,050 
1.950 
1,880 
1,780 
1.550 
1. 510 
1.390 
1.390 
1,270 
1,200 
1, 100 
1,050 
980 
960 
900 
800 


138  CHICAGO    METEOROLOGICAL   CONGRESS. 

Gauges  in  meters  and  discharges  in  cubic  meters  per  second,  etc. — Continued. 


Date. 


Maximum,  i878-'79.    '    Minimum,  A^^-'■}9,.    I      Mean  of  20  years. 

i 


Gauge. 


Apr.     I '  2.05 

5 '  2.01 

10 1. 98 

15 1-96 

20 1. 91 

„        25 1-87 

May     1 1.84 

5 1-73 

10 1-73 

15 I-7I 

20 1.64 

25 1.60 

31 1-55 

Month. 

June —  .57 

July .51 

August 4.82 

September ■  6. 83 

October t  8. 07 

November |  6. 29 

December 4.0S 

January 3. 05 

February 1  2. 48 

March 1  2.18 

April 1.94 

May 1.69 

Mean  of  the  year i  3.45 


Discharge.      Gauge.    ■   Discharge    1   Gauge. 


Discbarge. 


1,850 

28  i 

400 

1.05 

750 

1,830 

19   1 

380 

1. 00 

720 

1,740 

'? 

360 

•93 

650 

1,740 

06 

330 

•87 

600 

1,740 

01 

330 

.80 

570 

1, 550    — 

06 

290 

.76 

540 

1, 650    — 

15 

290 

.70 

500 

1,560    — 

'7   i 

270 

;    .68 

480 

1, 560    — 

21   1 

270 

1    .66 

470 

1, 560    — 

26 

240 

i    .61 

460 

1, 470   — 

30 

240 

.61 

430 

1,470   ,  — 

35 

200 

■56 

400 

1,380   — 

42 

1 80 

•50 

380 

175 

28   ! 

480 

•47 

400 

640   i   I 

16 

1, 120 

1-23 

1,090 

5,150    3.94  1 

3.930 

4.80 

4,930 

8, 250      4 

70   1 

4.780 

6.32 

7,040 

'.350      4-33   ! 

4,290 

6.35 

6,940 

7. 020      3 

20 

3.050 

4-30 

4.300 

4, 030      2 

18 

1,960 

2.86 

2,700 

2, 890    ]   I 

.■Sb 

1,400 

2.14 

1.950 

2,270 

89 

880 

1.64 

1.350 

1,950   j 

4b 

520 

1-30 

940 

1,740   ! 

07 

340 

.87 

620 

1.520   1  — 

30 

240 

.62 

440 

3, 920   1   I 

88 

1,910 

2.74 

2,730 

V. — Tables  and  Statistics. 

Miscellaneous  tables  of  times  and  heights  of  high  flood  and  low 
water  level,  disposal  of  the  water  of  the  Nile  between  Assu^n  and 
Cairo,  proportion  of  rainfall  discharged  into  the  sea,  and  approximate 
quantity  of  solids  discharged  into  the  sea  and  deposited  on  the  soil  of 
Egypt  in  an  average  year  at  the  present  time : 

Table  giving  dates  and  heights  of  the  real  minimum  at  Assudn. 
[Zero  of  the  gauue  means  "mean  low-water  level."] 


Meters.    1 

i873,June5 —0.37 

1874,  May  30 —  o.  64 

1875,  May  23 —0.17    I 

1876,  June  15 +0.13   1 

1877,  May  27 4-0.10 

1878,  June  23 —0.71'' 

1879,  May  23 +  I. SS*" 

1880,  J  une  9 +  o.  82 

1881,  May  14 4-  o.  00  J 

1882,  June  23 —  o.  55    I 

»  Worst  low  supply. 


Meters 

i883,June22 -f-  0.04 

1884,  May  27 -j-  0.37 

i885,June2 —  0.44 

1886,  June  3 —  0.06 

1887,  May  8 —  0.03 

1888,  Junes —  0.08 

1889,  June  24 —  0.60 

1890,  June  8 —  0.60 

1891,  May  19 —  0.21 

1892,  June  18 —  o.  64 

•"Best  low  supply. 


The  river  was  below  the  mean  low-water  level  thirteen  years,  and 
above  seven  years.  The  mean  of  the  minimum  is  — 0.08  meters. 
In  order  to  find  the  date  of  real  minimum  at  Cairo  add  twelve  days 
to  the  above  dates.  The  Cairo  gauge  at  this  stage  of  the  river  is 
valueless  as  the  regulation  at  the  Barrages  affects  it. 

Very  high  floods  scour  out  the  deepest  parts  of  the  river's  bed,  and 
a  gauge  of  —0.60  meters  in  1878  and  1889,  after  the  poor  floods  of  1877 


THE    NILE. 


139 


and  1888,  gave  a  discharge  25  per  cent  less  than  a  gauge  of  — 0.60 
meters  iu  1892  after  the  good  and  late  flood  of  1891. 

Table  giving  dates  and  heights  of  the  maximum  flood  levels  at  Assudn. 

[Zero  on  the  gauge  means  "  mean  low-water  level."] 


Meters.  \\ 


1873,  Sept.  1 7 

1874,  Sept.  6 8 

1875,  Sep.  II 8 

1876,  Sept.  7 8 

1877,  Aug.  20 6 

1878,  Get.  I 9 

1879,  Sept.  13 8 

1880,  Sept.  4 7 

1881,  Sept.  4 8 

1882,  Aug.  28 8 

»The  poorest  flood.      ^The  highest  flood 


883,  Sept.  17  . 

884,  Sept.  I   . 

885,  Aug.  23  . 

886,  Sept.  22 

887,  Sept.  I  . . 

888,  Aug.  24  . 

889,  Sept.  2.. 

890,  Sept.  2  . 

891,  Sept.  4. . 
8q2,  Sept.  20  , 


Meters. 


« Sept.  22,  7.60.     ii Sept.  10,  8.00.     'Sept.  27,  7.1 


The  late  and  very  high  flood  of  1892  is  being  followed  by  a  sum- 
mer supply  in  the  Nile  nearly  as  high  as  that  of  1879  after  the  very 
high  and  late  flood  of  1878. 

A  mean  high  flood  is  7.90  meters ;  the  mean  of  the  maximum  is 
8.17  meters. 

Table  giving  the  dates  and  heights  of  the  maximum  flood  levels  at   Cairo. 
[Zero  on  the  gauge  means  "mean  low-water  level."] 


Meters. 

1873,  Sept.  14 5. 86 

1874,  Oct.  6 8. 70" 

1875,  Oct.  18 7.44 

1876,  Sept.  27 7. 69 

1877,  Aug.  27 4-95 

1878,  Oct.  II 8. 56" 

1879,  Oct.  I 7.60 

1880,  Oct.  26 6.08 

1881,  Oct  13 7.38 

1882,  Oct.  28 6. 02 

»  Should  be  8.25. 


Meters- 

1883,  Oct.  II 7.38 

1884,  Oct.  25 6.52 

1885,  Oct.  18 6. 67 

1886,  Oct.  4 6.42 

1887,  Sep.  25 7.93 

1888,  Sept.  15 5.34 

1889,  Oct.  16 6. 74 

1890,  Oct.  25 7.12 

1891,  Oct.  25 6.72 

1892,  Oct.  7 7.93 

'•Should  be  8.15. 


In  1'874  and  1878  the  gauges  were  incorrectly  recorded  at  Cairo. 
Corrections  have  been  applied  by  calculations  from  the  Barrage 
gauges. 

The  most  serious  flood  of  the  century  was  that  of  1878,  but  what 
its  height  might  have  been  at  Cairo  will  never  be  known  as  the  Nile 
banks  were  swept  away  on  October  11,  while  the  Nile  was  rising. 

The  mean  of  the  maximum  is  6.95 ;  a  mean  high  flood  is  6.70. 

Table  giving  approximate  dates  on  which  maximum  and  real  minimum  guages  were 

reached  at  Assudn. 


Number  of  times  minimum. 


May  10. 
15. 
20. 
25. 

June    1.. 
5.. 
10 
15 
20 
25 


1 
1 
1 
4 
1 
2 
3 
1 
2 
4 

20 


Number  of  times  maximum. 


Aug.   20. 

25. 

Sept.    1  , 


10 
15 
20 
25 
1. 


Oct. 


1 
2 
6 
4 
1 
2 
2 
1 
1 

20 


140  CHICAGO   METEOROLOGICAL   CONGRESS. 

Table  giving  approximate  dates  on  which  maximum  and  real  minimum  gauges  were 

reached  at  Cairo. 
Number  of  times  minimum. 

May  20 1 

25 1 

June   1 1 

5 5 

10 3 

15 2 

20 3 

25 1 

July     1 1 

5 2 


Number  of  times  maximum, 

Aug.  25 1 

Sept.  15 2 

25 2 

Oct.      1 1 

6 3 

10 2 

15 3 

20 1 

26 5 


20 

20 

The  date  on  which  the  real  minimum  is  reached  is  the  last  day  of 
low  supply  before  the  final  rise  begins ;  occasionally  the  actual  mini- 
mum, a  few  centimeters  below  the  real  minimum,  precedes  the  latter 
by  many  days. 

Calculation  explainivg  the  consumption  of  water  in  an  average  year  between  Assudn 

and  Cairo. 

[An  Egyptian  acre  equals  4,200  square  meters.] 

Evaporation  off  the  basins —  Cubic  meters. 

1,500,000  acres  X  4.200  X  .008  daily  X  45  days  equals 2,268,000,000 

Evaporation  off  the  Nile  itself — 

950,000  meters  X  700  meters  X  2.00  meters  equals 1,330,000,000 

Irrigation  of  060,000  acres  of  land  perennially  irrigated — 

660,000  X  4,200  X  2.00  meters  equals 5,544,000,000 

Escapes  directly  into  the  Rosetta  branch 500,000,000 

Total  expenditure 9,642,000,000 


Cm.  per  sec. 

Mean  discharge  per  day  at  Assuan,  from  Appendix  III 3, 150 

Mean  discharge  per  day  at  Cairo,  from  Appendix  IV 2,730 

Balance  spent 420 


Total  quantity  of  water  expended  between  Assuan  and  Cairo 

in  one  year  equals  365  X  420  X  86,400,  amounting  to 13,245,000,000 

Therefore  the  quantity  of  water  absorbed  into  the  soil  per  annum  equals 
13,245,000,000  —  9.642,000,000  =  3,603,000,000  cubic  meters,  and 
as  this  is  absorbed  over  an  area  of  2,210,000  acres,  the  depth  of 
water  absorbed 

equals  ,3,603^000,000      ^  3^3  ^  ^^  meters. 
^         2,210,000  X  4,200      ^9,282 

Table  showing  the  amount  of  water  which  reaches  the  sea  in  an  average  year. 

From  Appendix  IV,  the  mean  discharge  at  Cairo  =:  2,730  cubic  meters  per  second. 

From  this  deduct  the  water  withdrawn   from  the  Nile  by  the  Delta  canals   north  of 

Cairo,  viz.: 

Cm.  per  sec.  Cm.  per  sec. 

January 300        August 1,000 

Februarv 300        September 1,200 

March..; 300         October 1,200 

April 300         November 500 

May 350         December 300 

June 400 

July 500            Mean  for  the  year 654 


THE    NILE. 


141 


Therefore  the  discharge  into  the  sea  =:  2,730  —  554  =  2,176  cubic  meters  per  second, 
or  68,600,000,000  cubic  meters  per  annum. 

As  the  average  rainfall  in  the  Nile  Basin  has  been  found  to  be  2,633,000,000,000  cubic 

meters  per  annum,  the  water  which  reaches  the  sea  :=  —  or  say  —  of  the  rainfall. 

39  -^  40 

Table  giving  the  quantity  of  solid  matter  carried  to  the  sea  by  the  Nile  in  an  average 

year. 

[See  proceedings  of  the  Institute  of  Civil  Engineers,  Vol.  LX,  i87g-'8o.) 


Month. 


Discharge  of 

the  Nile  at 

Cairo  in  cubic 

meters  per 

second. 


Discharge  of 

the  Delta 

canals. 


Discharge  en- 
tering the 


June 

July 

August 

September 
October ... 
November 
December. 
January... 
February  . 
March  .... 

April 

May 


400 
1,090 

4.930 
7,040 
6,940 

4.300 

2,700 

1.950 

1.350 

940 

620 

440 


400 

500 

1,000 

1,200 
1,200 
500 
300 
300 
300 
300 
300 
350 


590 

3.930 

5.840 

5.740 

3.800 

2,400 

1,650 

1,050 

640 

320 

90 


6.9- 

-100,000  =  0.0 

17.8-: 

-100,000=  .105 

149.2- 

-100,000  =  5.864 

54.3- 

-100,000  =  3.171 

37.8- 

-100,000  =  2.170 

34.4- 

-100,000  =  1.307 

28.9- 

1-100,000=  .694 

16.7- 

-100,000=  .276 

12.6- 

h  100,000=  .132 

5.3- 

-100,000=  .034 

6.6- 

-100,000=  .021 

4.8- 

-100,000=  .004 

Solids  carried  in  suspension  in  cubic  meters  per  second. 

June OX 

July 590  X 

August 3,930  X 

September  5,840  X 

October 5,740  X 

November 3,800  X 

December 2,400  X 

January 1,650  X 

February 1,050  X 

March 640  X 

April  320  X 

May 90  X 

Mean 1.1465 

Total  quantity  of  solids  carried  to  the  sea  in  an  average  year  equals 

365  X  1.1465  X  86,400  =  36,156,000  cubic  meters  or  tons. 

Table  giving  the  approximate  quantity  of  solid  matter  carried  by  the  Nile  at  Assv^n 

in  an  average  year. 
[From  Table  III.    Solids  carried  in  .luspension  in  cubic  meters  per  second.] 

June 660  X 

July 2.080  X 

August 7,850  X 

September  9,810  X 

October 6.400  X 

November 3,550  X 

December 2,380  X 

Janwary 1,750  X 

Februarv 1,280  X 

March  .' 920  X 

April 630  X 

May 500  X 

Mean 1-907 


6.9- 

-100,000  = 

.045 

17.8- 

-  100.000  = 

.370 

149.2- 

-100,000  = 

11.712 

54.3- 

-100.000  = 

5.327 

43  - 

-100.000  = 

2.752 

40  - 

-100,000  = 

1.420 

28.9- 

-100,000  = 

.690 

16.7- 

-  100.000  = 

.292 

12.6- 

-100,000  = 

.161 

5.8- 

-100,000  = 

.049 

6.6- 

-  100.000  = 

.042 

4.8- 

-  100,000  = 

.024 

142  CHICAGO    METEOKO LOGICAL   CONGRESS. 

Total  quantity  of  solids  carried  past  Assuan  in  an  average  year  equals 

365  X  1.907  X  86,400  =  60,160,000  cubic  meters. 
Quantity  of  solids  deposited  on  the  soil  of  Egypt  equals 

60,150,000  —  36,156,000  =  23,994,000,  or  24,000,000  cubic  meters  per  annum. 
As  the  area  over  which  this  is  deposited  is  4,950,000  acres,  the  depth  deposited  per 
100  years  equals 

24,000,000        _ 
4,950,000  X  4,200  —-^^^  meter.s. 

Before  basin  irrigation  was  changed  into  perinnial  irrigation  over  two-thirds  the  area 
of  Egypt  the  mean  deposit  must  have  been  considerably  greater. 


8.— THE  BEST  MEANS  OF  FINDING  RXTLBS  FOR  PREDICTING 
FLOODS  IN  WATER  COURSES. 

M.  Babixkt. 

It  does  not  appear  to  me  possible  to  exhaust  in  a  few  pages  the 
subject  proposed  to  M.  Lemoine,  Inginieur  en  Chef  des  Fonts  et 
Chaiissees  at  Paris,  in  charge  of  the  Central  Hydrometric  Service  in 
the  Basin  of  the  Seine,  by  the  Honorable  President  of  Section  II  of 
the  International  Congress  of  Meteorology,  held  at  Chicago  in  the 
month  of  August,  1893. 

Very  happily,  the  task  to  be  fulfilled  is  well  defined  by  a  very  clear 
programme,  to  which  we  reply  with  our  best  effort,  but  of  which  the 
last  two  questions  apparently  ought  to  be  interchanged  for  clearness 
of  exposition. 

QUESTION    I. 

What  ought  loe  to  propose  to  ourselves  in  the  matter  of  flood  predictions; 
ought  prediction  to  be  general  or  specific  as  regards  the  stations  and  the 
levels  which  we  are  to  expect  there  f 

It  is  not  very  difficult  to  predict  that  a  flood  river  is  going  to  rise 
when  one  has  knowledge  of  abundant  rains  fallen  over  its  basin ;  the 
consequences  are  particularly  grave  in  the  higher  portions  of  the 
country  when  the  impermeability  of  the  soil  is  there  very  marked ; 
the  slopes  of  the  land  there  facilitate  in  every  instance  the  superficial 
draining  or  deter  evaporation  or  absorption  by  the  soil.  So,  then,  one 
may  rely  on  a  few  rain  gauges  judiciously  distributed  and  connected 
with  a  central  station  as  sufficiently  adequate  to  organize  a  system  of 
flood  predictions. 

Date  of  maximum. — This  first  result  which,  moreover,  must  not  be 
considered  as  altogether  negligible,  may  be  improved  if  we  strive  to 
forewarn  the  inhabitants  of  a  determined  locality,  in  place  of  simply 
predicting  a  rising  of  the  level  of  the  water  in  a  whole  region..  We 
shall  soon  be  led  to  state  precisely  the  epoch  when   the  level  will 


RULES    FOR    PREDICTING    FLOODS.  143 

attain  its  greatest  height  at  the  place  considered,  from  similar  phe- 
nomena observed  up  the  stream  and  signaled  by  the  telegraph. 

The  importance  of  the  principle  of  the  time  of  propagation  of  the 
maximum  is  thus  made  evident. 

Importance  of  the  flood. — We  can  not  admit  that  a  flood  has  been 
thoroughly  announced  if  we  content  ourselves  with  indicating  merely 
the  time  of  its  passage  at  such  and  such  a  point  without  troubling 
ourselves  with  the  level  it  is  to  attain.  Even  when  the  insufficiency 
of  previous  investigation  and  verification  does  not  allow  of  detailed 
predictions,  if  the  service  is  content  with  simple  warnings,  there 
can  generally  be  added  to  the  word  flood  a  qualifying  word,  such  as 
feeble,  mean,  or  strong.  This  is  a  first  approximation  ordinarily 
realizable  everywhere  from  the  recollections  of  the  people  of  the 
country,  or  from  the  mean  of  a  small  number  of  observations. 

Numerical  'predictions. — To  go  further  and  hazard  the  indication  of 
a  stage  of  determined  height  on  an  invariable  river  gauge,  it  is 
certainly  preferable  to  be  able  to  make  numerous  comparisons  be- 
tween a  large  number  of  occurrences  of  high  water.  However,  the 
illustrious  Belgrand,  founder  of  the  Hydrometric  Service  in  the  Basin 
of  the  Seine  in  1854,  whose  researches  are  appreciated  to-day  in  the 
entire  world,  did  not  take  more  than  two  years  to  establish  a  formula 
for  predicting  three  days  in  advance  the  total  rise  of  the  Seine  at 
Paris  from  those  of  the  upper  tributaries,  as  shown  by  eight  well- 
chosen  stations  toward  the  limit  of  the  most  distant  impermeable 
lands  drained.  In  spite  of  the  apparent  complication  of  the  basin 
of  the  Seine,  where  the  water  courses  of  equivalent  importance  are 
numerous  with  their  superficial  drainage  converging  on  the  outskirts 
of  Paris,  the  same  principles  applied  with  perseverance  by  M.  G. 
Lemoine,  pupil  of  Belgrand,  and  by  his  co-workers,  have  allowed  of 
predicting  for  the  past  twenty  years  the  probable  levels  of  the  impor- 
tant floods  on  the  Seine  and  principal  tributaries  to  within  30  or  40 
centimeters,  or  better. 

Similar  studies  inspired  or  not  by  the  same  principles  have 
succeeded  as  well  elsewhere.  They  have  been  instituted  in  France 
(1st)  on  the  Loire  at  Orleans,  (2d)  the  basin  of  the  Meuse  almost 
exactly  at  the  time  when  Belgrand  drew  from  the  first  results  a  new 
science  of  hydrology  of  which  the  announcement  of  floods  is  only  an 
application,  (3d)  on  the  Saone,  the  Garonne,  the  upper  and  lower 
Loire,  and  more  recently  in  several  parts  of  the  basin  of  the  Rhone. 
They  did  as  much  in  Italy  for  the  basins  of  the  Arno  and  the  Tiber 
about  1866,  a  little  later  on  the  Elbe  in  Bohemia,  and  finally  on  the 
Ohio  and  Mississippi  in  the  United  States  since  1884.  Without  con- 
sidering the  most  convenient  processes  for  each  basin,  according  to 
its  configuration  and  the  lands  that  compose  it,  we  can  affirm  the 
possibility   of  predicting  floods  almost  everywhere  outside   of  the 


144  CHICAGO    METEOROLOGICAL   CONGRESS. 

mountainous  regions  where  they  are  formed,  and  where  their  ravages 
are  less  to  be  dreaded  than  in  the  fertile  plains  menaced  by  the  over- 
flow of  water. 

QUESTION    II. 

What  arrangement  of  hydrometric  stations  on  the  principal  rivers  and 
on  their  tributaries  is  the  most  advantageous  for  predicting  levels  ? 

The  choice  of  means  to  be  employed  for  announcing  floods,  and 
particularly  numerical  predictions  of  heights  on  certain  gauges,  de- 
pends essentially  on  the  time  available  for  concentrating  the  infor- 
mation as  to  the  stages  at  points  along  the  upper  courses  and  the  time 
required  for  giving  information  of  their  results  to  points  lower  down. 
The  number  of  hours  depends  materially  on  the  rapidity  of  propaga- 
tion of  the  wave,  but  the  facility  of  transmission  of  the  warnings 
principally  by  telegraph  plays  also  an  important  role  and  at  times 
preponderates  in  the  question. 

A.  Long-time  forecasts  by  means  of  upper  tributaries. — However  per- 
fect may  be  the  communication  from  one  point  to  another  along 
a  w^ater  course,  it  is  always  advantageous  to  note  the  indications  as 
far  up  the  river  as  possible.  In  this  method  we  are  only  limited  by 
the  multiplicity  of  nearly  equal  influences  of  which  it  is  then  neces- 
sary to  take  account. 

Thirty  or  forty  years  ago  the  French  telegraph  system  was  yet 
little  developed.  Warnings  were  mostly  sent  by  post.  In  order  to 
have  time  to  receive  data  for  the  problem  Belgrand  had  taken  typical 
stations  in  the  circumference  of  the  Seine  basin  at  a  convenient  dis- 
tance from  the  water-parting,  approximately  on  the  arc  of  a  circle  of 
which  Paris  is  almost  the  center.  He  remarked,  moreover,  that  in 
these  regions,  as  everywhere  else,  the  water  courses  from  impermeable 
land  carry  off  almost  all  the  rain  that  falls  over  their  drainage  areas, 
consequently,  they  determine  the  beginning  and  maximum  of  floods. 
In  the  basin  of  the  Seine  the  permeable  lands  cause  the  level  to  be 
sustained  for  a  period  of  greater  or  less  length,  according  to  the 
duration  of  the  rain,  after  the  complete  saturation  of  the  soil ;  their 
levels  rise  and  fall  slowly,  and  their  influence  is  more  often  negligible 
or  very  secondary. 

B.  Short-time  forecasts  by  means  of  several  upper  observation  stations. — 
The  observation  stations  used  for  the  announcement  of  floods  at 
Paris,  so  reduced  to  eight,  are  yet  sufficiently  numerous  for  their 
influence  on  the  result  to  vary  a  little  from  one  flood  to  another, 
according  as  the  rise  is  earlier  or  later  at  one  point  or  the  other. 
Thanks  to  the  actual  rapidity  of  the  telegraphic  transmission,  the 
indications  that  one  receives  thus  from  the  most  distant  observers 
serve  to  establish  three  days  in  advance  at  least  a  first  approximation, 
subject  to  correction  by  subsequent  warnings  from  nearer  stations. 


RULES    FOR    PREDICTING    FLOODS.  145 

For  these  corrections,  as  well  as  for  announcements  destined  for 
certain  stations  less  distant  from  the  water-parting,  we  can  utilize 
the  relations  which  generally  connect  the  maximum  level  prob- 
able at  one  given  point  with  the  corresponding  levels  observed  by- 
two  gauges  situated  up  the  stream  on  the  two  most  important  water 
courses  of  which  the  union  forms  the  one  which  passes  by  the  place 
considered.  In  order  that  a  relation  between  three  heights  of  water 
thus  chosen  may  be  utilized,  it  is  sufficient  that  the  first  two  stages  be 
known  long  enough  before  the  realization  of  the  third  which  results 
from  it.  It  is  thus  that  the  levels  observed  on  the  Seine  at  Paris,  and 
on  the  Oise  at  Compiegne,  allow  of  announcing  the  maximum  of  the 
Seine  at  Mantes  the  next  day.  The  floods  of  the  Marne  at  Epernay, 
and  of  the  Yonne  at  Sens,  among  others,  are  generally  predicted  in 
their  details  by  the  same  process.  On  many  rivers  whose  basins 
have  not  the  same  configuration  as  that  of  the  Seine,  and  where  the 
propagation  of  floods  is  much  more  rapid,  it  may  happen  that  this 
arrangement  of  observations  gives  by  itself  good  results  in  practice. 

If  there  are  more  than  three  water  courses  of  equal  importance,  the 
corresponding  heights  of  water  of  the  affluents  may  be  combined, 
forming  a  mean,  which  may  be  treated  as  the  actual  stage  at  a 
second  upper  station,  as  in  the  case  cited  above.  It  is  in  this  way 
the  announcements  of  floods  on  the  Loire  are  made  at  Nevers. 

C.  Use  of  a  single  station  at  a  point  above. — The  problem  is  much 
simplified  if  the  principal  water  course  receives  no  important  affluent 
for  a  distance  sufficient  for  the  announcement  of  floods  to  precede 
their  occurrence.  It  is  this  that  happens  first  for  the  Loire  between 
the  points  where  it  receives  successively  the  Allier  below  Nevers  and 
the  Cher  at  Tours,  second  for  the  Saone  up  the  river  to  Lyons  from 
the  confluence  of  the  Doubs.  In  this  case  the  maximum  to  be  pre- 
dicted for  the  lower  gauge  is  a  function  of  a  single  variable  which 
represents  the  level  attained  on  the  upper  gauge.  If  we  develop  this 
function  in  series  according  to  the  increasing  powers  of  the  variable, 
we  can  at  times  neglect  the  second  and  higher  powers  when  the  series 
is  converging ;  the  result  is  the  same  as  if  we  admitted  a  priori  the 
proportionality  between  the  two  stages. 

To  facilitate  the  announcements,  the  length  of  river  unprovided 
with  affluents  ought  to  be  greater  in  proportion  as  the  slope  is  more 
rapid  and  gives  to  the  water  course  in  consequence  a  character  more 
torrential.  It  is  impossible  to  establish  very  precise  general  regula- 
tions on  this  subject,  for  in  France,  at  least,  the  speed  of  propagation 
of  the  maximum  varies  much  from  one  river  to  another  and  on  the 
same  river  in  different  parts  of  its  course;  it  does  not  exceed  4 
kilometers  an  hour  on  the  Saone  or  on  the  Seine  below  Paris,  while 
it  attains  6  kilometers  on  the  Garonne,  8  to  10  kilometers,  and  some- 
times more,  on  the  Rhone  or  the  Durance.  We  must  have  at  least 
10 


146  CHICAGO    METEOROLOGICAl   CONGRESS. 

twelve  hours  interval  before  us  after  the  maximum  occurs  up  the 
river  in  order  to  give  warnings  to  points  below ;  this  is  even  insuffi- 
cient if  the  rise  is  rapid  and  occurs  in  a  night. 

D.  Importance  of  the  determination  of  the  maximum. — Self -recording 
apparatus. — Whatever  may  be  the  arrangement  of  the  observing  sta- 
tions, according  to  circumstances,  we  can  not  insist  too  strongly  on 
the  necessity  of  knowing  exactly  the  maximum,  its  height,  and  the 
exact  moment  it  occurs  at  each  gauge  in  order  to  make  precise  com- 
parisons. The  natural  law,  according  to  which  a  variable  quantity 
changes  slowly  in  value  in  the  neighborhood  of  a  maximum  or  a 
minimum,  and  more  rapidly  in  every  other  case  during  the  intervals 
between  them  prevents  making  any  verj"  great  errors  in  this  matter 
in  tranquil  rivers  whose  regimen  is  permanent. 

The  difl&culties  are  much  greater  on  certain  torrential  affluents  where 
the  observations  at  fixed  hours,  however  close  together  they  may  be  in 
times  of  flood,  allow  the  most  interesting  heights  to  be  missed  and  also 
the  moment  of  their  occurrence.  In  order  to  guard  against  this  incon- 
venience, self-registering  apparatus  of  various  kinds  is  beginning  to  be 
be  employed  in  France,  not  only  in  Paris  and  its  outskirts,  but  particu- 
larly in  the  basin  of  the  Durance,  the  principal  affluent  of  the  Rhone, 
where  the  slope  of  the  water  courses  and  the  rapidity  of  their  floods 
are  quite  exceptional.  This  means  of  investigation  can  not  be  passed 
over  in  silence  to-day,  and  will  probably  permit  of  pursuing  investi- 
gations, which  otherwise  would  not  give  any  important  result. 

QUESTION    III. 

What  are  the  best  methods  for  finding  rides  for  announcing  floods  f 
According  to  the  difficulties  considered  in  the  above  paragraphs.  A, 
B,  C,  and  D,  two  general  processes  are  recommended  for  forecasting 
the  levels  of  rivers  at  stations :  ( 1 )  by  utilizing  the  risings  of  the 
principal  water  course  and  its  affluents,  that  is  to  say,  the  differences 
between  the  minimum,  where  the  rise  of  water  begins  (initial  stage) 
and  the  maximum,  where  it  ceases.  (2)  By  comparing  the  highest 
absolute  stages  that  the  water  reaches  successively  at  different  points 
during  the  considered  flood. 

1.  Announcement  of  floods  by  rises. — The  first  process  is  alone  applica- 
ble to  the  long-time  predictions  of  paragraph  A  ;  this  is  what  Belgrand 
employed  for  announcing  the  floods  on  the  Seine  at  Paris  in  1856.  It 
eliminates  an  important  source  of  error  by  taking  count  of  the  ine- 
qualities of  the  initial  stage  on  the  gauge  for  which  the  predictions  are 
made.  To  this  stage  (variable  according  to  the  circumstances  which 
have  preceded  the  flood  considered )  we  add  a  probable  rise  calculated 
by  the  aid  of  the  actual  rises  at  the  stations  of  observation  above ;  it 
will  generally  be  a  function  of  the  first  degree  if  the  development  of 
the  series  which  corresponds  to  the  influence  of  each  gauge  up  the 
river  allows  of  considering  them  as  converging  rapidly  enough. 


RULES    FOR    PREDICTING    FLOODS.  147 

The  study  of  the  rises  is  particularly  indispensable  if  one  considers 
a  multiple  flood ;  that  is  to  say,  if  a  continued  great  elevation  of 
water  on  the  gauge  is  produced  by  many  distinct  oscillations  of  the 
water  up  stream.  The  case  is  presented  frequently  at  Paris,  and  in 
the  outskirts,  where  the  waters  supplied  to  the  upper  affluents  unite 
from  successive  falls  of  rain.  The  case  in  point  is  due  to  the  per- 
meable lands  from  which  the  waters  arrive  late  after  those  of  the  im- 
permeable lands  and  sustain  their  floods.  The  highest  stages  attained 
by  the  affluents  do  not  then  permit  of  foreseeing  directly  the  maxi- 
mum down  the  river  as  one  would  hope  if  there  was  only  a  single 
rise  at  each  station  up  stream. 

We  try,  often  with  success,  to  take  for  the  probable  rise  at  the  sta- 
tion a  simple  mean  of  observed  rises  on  the  upper  secondary  basins 
by  taking  count  of  the  inequality  of  the  surfaces  and  of  the  partic- 
ular degree  of  impermeability  of  each  one  of  them  by  appropriate 
coefficients,  or  by  the  choice  of  many  stations  in  the  same  basin,  as 
Belgrand  has  done  by  taking  at  the  same  time  the  rises  of  the  Marne 
at  Chaumont  and  at  St.  Dozier  for  announcement  at  Paris. 

If  the  hypothetical  relation  between  the  rises  up  and  down  stream 
does  not  appear  to  be  sufficiently  simple,  the  proceedings  indicated  in 
the  outline  sketch  by  Mr.  D.  Deague  (Gauthier  Villars,  1892,  pp. 
65-81),  will  permit  of  giving  to  it  a  graphic  representation;  if 
necessary,  one  can  state  the  equations  of  relation  by  means  of  un- 
known coefficients,  and  determine  those  coefficients  by  the  method 
of  least  squares,  so  as  to  satisfy  in  the  best  way  a  certain  number  of 
observed  cases ;  but  this  method,  very  laborious,  has  the  inconve- 
nience of  not  well  taking  account  of  the  natural  circumstances  by 
which  the  floods  are  distinguished. 

Some  rapid  "  trials,"  without  direct  solution,  led  to  the  same  re- 
sults, as  has  been  demonstrated  by  Inspector  General  Allard  (Annales 
des  Fonts  et  Chaussees,  1889,  ler  sem.,  Le  Seine,  Tome  i,  p.  631). 

Nothing  proves,  moreover,  that  the  relation  above  mentioned  should 
be  a  continuous  function  of  the  variables  it  represents,  and  there  are 
even  some  chances  that  it  may  be  otherwise  when  the  real  rises  sur- 
pass certain  critical  points,  at  some  stations,  such  as  certain  levels  of 
submersion  beyond  which  the  wetted  perimeter  of  the  bed  of  the  river 
changes  quickly. 

One  is  thus  led  to  form  categories  of  similar  floods  for  a  given  sta- 
tion and  to  modify  the  formula  of  prevision  according  to  the  catego- 
ries. A  trial  of  this  kind  has  been  made  quite  recently  for  many 
gauges  in  the  basin  of  the  Oise,  but  in  such  cases  there  is  great  dan- 
ger of  multiplying  too  much  the  particular  cases  so  that  they  are  not 
readily  recognizable. 

By  taking  as  abscissae  a  conveniently  chosen  function  of  the  rises 
at  certain  of  the  upper  stations  and  as  ordinates  a  similar  function 


148  CHICAGO    METEOROLOGICAL    CONGRESS. 

of  all  the  others,  and  writing  by  the  side  of  the  point  thus  deter- 
mined the  actual  corresponding  rise  observed  at  the  station  for  which 
the  prediction  is  to  be  made,  the  locus  of  the  points  of  equal  stage 
may  be  considered  as  the  projection  of  a  curve  of  levels  of  a  surface 
which  will  give  some  idea  of  how  the  rises  in  question  are  related. 

2.  Predictions  by  absolute  stages. — This  representation  of  a  law  estab- 
lished between  many  variable  quantities  is  utilized  by  M.  Mazoyer  for 
the  announcement  of  the  floods  of  the  Loire  at  Nevers  (Annales  des 
Fonts  et  Chnuss^es,  1890,  2d  sem.,  Tome  xx,  pp.  441-511) ;  but  in  place 
of  rises  the  highest  levels  attained  at  each  point  are  considered.  A 
similar  graphical  process  had  been  in  use  since  1882  for  studying  the 
relation  between  the  maximum  of  the  Seine  at  Rouen,  that  of  the 
Seine  at  Mantes,  and  the  level  of  the  open  sea  at  Havre,  about  thirty- 
six  hours  after  this  latter. 

If  we  consider  the  simple  floods  in  which  the  elevation  of  the  water 
observed  at  a  station  arises  from  a  single  similar  movement  observed 
at  a  distant  station  up  stream  without  any  intermediate  affluent,  the 
comparison  of  rises  is  no  longer  essential.  The  highest  levels  attained 
at  both  places  are  then  generally  in  direct  relation ;  in  taking  the 
first  as  abscissa?,  the  second  as  ordinates,  we  o.ften  find  that  the  ex- 
tremities of  the  latter  depart  but  little  from  a  regular  curve  which  is 
useful  in  making  predictions.  The  Hydrometric  Service  of  the  Basin 
of  the  Seine  has  established  many  graphics  of  this  kind  which  it 
uses  to  great  advantage. 

It  goes  without  saying  that  the  above  curves  may  be  replaced  by 
tables  of  single  or  double  entry ;  this  latter  process  has  been  in  pref- 
erence employed  by  M.  Jollois  for  the  floods  of  the  upper  Loire 
{An7iales  des  Fonts  et  Chaussees,  1881,  ler  sem.,  Tome  i,  pp.  273-322). 

CONCLUSION. 

The  rules  just  considered  for  predicting  floods  are  quite  simple 
enough ;  for  finding  them  or  making  application  of  them,  it  suffices 
to  observe  exactly  the  heights  of  the  water,  either  by  the  eye  directly 
or  by  self -registering  apparatus  well  maintained.  It  seems  certain 
that  we  may  obtain  thus  in  most  cases  satisfactory  predictions,  par- 
ticularly by  carefully  studying  the  conditions  supplied  by  the  greatest 
known  floods. 

Predictions  by  means  of  discharges. — A  method  rather  more  com- 
plicated, of  which  the  principle  is  due  to  M.  Harlacher,  Professor  at 
the  Higher  Technical  School  at  Prague,  gives,  it  appears,  good  results 
on  the  Elbe  in  Bohemia.  It  might  be  recommended  in  analogous 
circumstances,  though  it  can  not  be  made  use  of  very  easily  in  many 
other  cases  such  as  described  above.  It  presupposes  essentially  that 
the  progression  of  the  floods  at  a  station  depends  exclusively  on  the 
heights  observed  at  several  stations  up  the  stream  sufficiently  distant 


RULES    FOR    PREDICTING    FLOODS.  149 

from  the  point  to  permit  of  sending  warnings  in  time  to  be  useful 
without  the  rains  or  affluents  of  the  intermediate  region  playing  any- 
important  part.  It  is  necessary,  moreover,  to  have  determined  for 
each  gauge  an  exact  relation  between  the  height  of  water  and  the  dis- 
charge per  second,  which  presupposes  long  and  minute  investigations 
carried  on  by  the  same  persons  in  order  to  make  them  comparable. 

If  the  stations  of  observation  are  so  situated  that  the  water  passing 
them  reaches  the  lower  station  at  the  same  time  there  can  be  deduced 
from  the  heights  observed  at  the  points  above  the  corresponding  dis- 
charges, and,  by  a  simple  addition,  the  discharge  down  stream,  which 
determines  the  height  to  be  there  expected.  This  metljod  ought  to 
give  the  best  results  when,  at  the  stations  above,  the  discharge  is 
strictly  defined  by  the  height  of  the  water  (which  pre-supposes  in- 
closed valleys,  on  which  a  great  variation  of  level  can  be  observed 
for  a  small  change  of  discharge),  and  that  at  the  same  time  down 
stream  an  appreciable  error  in  discharge  does  not  involve  a  great 
uncertainty  in  the  height  of  water  (which  will  happen  only  in  a  flat 
valley  with  a  large  broad  bed).  These  conditions  do  not  always 
happen  to  be  united.  The  Central  Hydrometric  Service  of  the  Basin 
of  the  Seine  has  tried  to  apply  the  method  of  M.  Harlacher  for  pre- 
dicting one  day  in  advance  the  probable  maximum  at  Paris  from 
those  of  the  Seine  at  Melun,  and  of  the  Marne  at  Chalifert  (near 
Meaux),  l")ut  without  success.  The  curves  of  relation  between  the 
heights  of  water  and  the  discharges  were  perhaps  not  exact  enough ; 
those  of  M.  Harlacher  are  the  result  of  eighteen  years'  continued 
research  without  change  of  supervision  or  control. 

Predictions  based  on  observations  of  rainfall. — Finally,  in  the  im- 
permeable basins  of  certain  torrential  rivers  with  heavy  slopes,  the 
time  available  for  making  predictions  from  heights  of  water  ascer- 
tained up  stream,  even  near  the  watershed,  would  be  quite  insufficient ; 
a  case  is  presented  in  France,  notably  in  the  water  courses  which  flow 
from  the  Cevennes  toward  the  Rhone  and  toward  the  Mediterranean. 
As  the  floods  are  at  times  exceptionally  disastrous  in  that  region,  M. 
G.  Lemoine  has  quite  recently  proposed  to  determine  precisely  the 
relations  between  their  height  and  that  of  the  rain  falling  some  days 
before.  The  commission  for  predicting  floods,  instituted  since  1875 
under  the  Minister  of  Public  Works,  has  had  established  provisional 
flood-warning  services  predicting  on  this  principle.  The  relations 
sought  for  will  probably  be  indicated  most  precisely  by  means  of  self- 
registering  rain  gauges.  Investigations  of  this  sort  seem  to  be  the  order 
of  the  day ;  one  may  get  an  idea  of  them  by  consulting  the  Annales 
des  Fonts  et  Chaussees,  1888,  ler  sem.,  Tome  xv,  pp.  464-510;  and  1892, 
ler  sem.,  Tome  iii,  pp.  166-196.  But  they  are  still  theoretical  rather 
than  practical,  and  it  remains  for  the  future  to  perfect  them. 


SECTION    III. 

MARINE   METEOROLOGY. 


1.— THE  FORECASTING-  OF  OCEAN  STORMS  AND  THE  BEST 
METHODS  OF  MAKING  SUCH  FORECASTS  AVAILABLE  TO 
COMMERCE. 

William  Allingham. 

Every  seafarer  will  very  readily  admit  that  the  forecasting  of  such 
dread  meteors  as  ocean  storms  is  a  far  easier  matter  in  theory  to  the 
few  than  in  practice  to  the  many.  Hence,  I  approach  a  considera- 
tion of  this  intensely  interesting  and  highly  important  subject  with 
a  feeling  of  diffidence  verging  on  despair.  The  interval  allotted  for 
reading  the  paper  is  necessarily  limited,  the  field  for  discussion  so 
vast  and  fertile,  that  for  mortal  to  command  success  in  his  venture 
is  impossible,  however  much  he  may  strive  to  deserve  it.  Nautical 
men  there  are,  under  every  sky  in  the  wide  world's  navies,  whether  of 
peace  or  of  war,  thoroughly  competent  to  treat  the  vexed  question  of 
ocean  storms  from  a  higher  plane  than  I.  The  arduous  duties  of  our 
noble  but  neglected  profession,  however,  too  often  preclude  close 
application  to  clerkly  work  of  this  nature,  and  mankind  is  thereby 
a  decided  loser.  I  have,  therefore,  accepted  the  invitation  which  you 
have  done  me  the  honor  to  give,  as  an  earnest  that,  in  the  words  of 
the  illustrious  Maury,  a  seaman  is  fit  for  other  things  than  tacking 
ship  or  washing  down  decks ;  and  in  the  sincere  desire  to  arouse  sea- 
farer's of  every  nation  not  only  to  assist  in  weather  work  by  recording 
observations  at  sea  and  in  unfrequented  ports,  but  also  by  taking  a 
far  more  active  part  in  conferences  at  which  nautical  matters  are 
brought  forward  for  detailed  discussion. 

The  forecasting  of  ocean  storms  is  of  great  utility,  both  to  those 
that  go  down  to  the  sea  in  ships  and  to  those  who  prefer  to  gaze 
upon  the  mighty  ocean  from  dry  land.  I  have,  consequently,  deemed 
it  necessary  to  deal  wdth  the  subject  chosen  for  me  from  both  points 
of  view.  A  navigator,  remote  from  the  land  and  the  electric  tele- 
graph, is  perforce  his  own  forecaster  of  ocean  storms ;  and  the  gravest 
responsibility  attaches  to  his  decision,  inasmuch  as  a  misinterpreta- 
tion of  the  scanty  data  at  hand  may  tend  to  the  total  loss  of  his 
160 


I 


FORECASTING    OF    OCEAN    STORMS.  151 

devoted  bark  and  all  her  crew.  He  will  rely  upon  such  signs  as  sky 
and  sea  afford  to  men  whose  lives  are  spent  in  continual  conflict  with 
the  elements  ;  while,  at  the  same  time,  not  unmindful  of  instrumental 
indications  and  the  published  deductions  from  the  experience  of 
navigators  who,  in  some  instances,  will  long  since  have  passed  away 
down  the  dim  corridors  of  time.  An  overwhelming  torrent  of  litera- 
ture relating  to  the  law  of  storms  has  flooded  the  market  since  it 
was  first  formulated,  and  the  ebb  is  not  yet.  It  would,  however,  be 
utterly  unsafe  to  assume  that  increased  certainty  has  been  borne  on- 
ward by  the  turbulent,  frothy  stream  of  words,  either  as  to  the  law 
itself  or  the  deductions  therefrom  embodied  in  so-called  rules  for 
handling  a  ship  that  she  may  altogether  avoid,  or  partially  utilize, 
the  winds  of  a  cyclonic  storm.  Despite  the  immense  amount  of 
labor  bestowed  upon  tracking  these  meteors  by  the  aid  of  syn- 
chronous charts,  I  am  reluctantly  compelled  to  confess,  without 
reserve,  that  navigators  have  not  been  supplied  with  much  informa- 
tion of  really  practical  value  with  respect  to  ocean  storms  subsequent 
to  the  discovery  that  they  are,  generally  speaking,  circular  whirls  of 
varying  size  and  energy ;  moving  onward,  now  fast,  now  slow,  over 
the  waste  of  waters.  The  sailor  is  unable  to  depend  implicitly  on 
the  curiously  contradictory  conclusions  of  modern  professional  and 
amateur  weather  workers.  He  not  infrequently  finds  that  his  own 
watchfulness  and  faculty  for  generalization  are  much  more  essential 
to  safety  than  all  the  drawing-room  storm  maneuvers  in  existence. 
Forecasting  of  storms  at  sea  involves  a  rapid  approximation  to  the 
values  of  several  variable  quantities ;  and,  having  regard  to  the 
indisputable  fact  that  weather  workers  on  shore,  although  assisted  as 
far  as  possible  by  electric  communication  with  outlying  districts, 
occasionally  forecast  a  storm  which  fails  to  put  in  an  appearance,  or 
let  one  slip  in  on  them  unwittingly,  there  is  matter  for  congratula- 
tion that  navigators  come  out  of  the  ordeal  by  wind  and  wave  so 
well.  To  insure  an  exact  result  to  any  given  prediction  of  an  ocean 
storm  the  anxious  but  self-reliant  mariner  must  know  the  bearing  of 
its  center,  its  distance  from  the  ship,  the  direction  whither  it  is 
traveling,  and  its  rate  of  motion  onward.  Need  I  say  that  the 
modern  book  compiler,  in  a  hurry,  has  only  helped  to  make  confusion 
worse  confounded  as  regards  our  knowledge  of  these  points.  I  most 
heartily  agree  with  a  statement  referring  to  ocean  storms  made  by  a 
well-known  navigator,  Capt.  S.  T.  S.  Lecky,  R.  N.  R.,  that  "we  can 
not  but  feel  that  to  a  great  extent  their  origin,  shape,  and  move- 
ments are,  as  yet,  purely  matters  of  speculation.  So  much  that  is 
contradictory  is  daily  appearing,  and  such  various  plausible  theories 
are  being  propounded,  that  it  is  most  difficult  to  arrive  at  any  safe 
and  practical  conclusion." 

Probably  no  great  discovery  has  ever  flashed  upon  the  world  unless, 


152  CHICAGO    METEOROLOGICAL    CONGRESS. 

and  until,  a  path  had  been  cleared  through  a  dense  growth  of  rank 
weedB  of  empiricism,  and  doubtless  many  a  one  came  within  almost 
measurable  distance  of  the  law  of  storms  prior  to  the  advent  of  Red- 
field.  The  first  hurricane  on  record  is  perhaps  that  which  Christopher 
Columbus  and  his  hardy  toilers  on  an  unknown,  awe-inspiring  sea 
endured  for  three  days  and  nights  of  leaden-footed  hours  in  their  tiny 
craft  near  the  Azores  in  February,  1493.  It  is,  therefore,  peculiarly 
appropriate  for  prominent  mention  in  this  paper  when  all  the  world 
and  his  wife  have  set  their  faces  toward  the  Columbian  Exposition  at 
Chicago.  Even  five  centuries  ago  seafarers  noticed  that  the  storm- 
wind  did  not  blow  unceasingly  from  one  direction  only,  but  from 
several  points  of  the  compass  in  succession.  The  Philosophical  Trans- 
actions of  1698  contain  a  clearly-drawn  word  picture  of  West  Indian 
hurricanes  by  a  Capt.  Langford,  who  was  evidently  intimately  ac- 
quainted with  some  of  these  undesirable  visitors.  This  old-time  navi- 
gator pointed  out  that  a  West  Indian  hurricane  is  a  whirlwind,  in 
which  the  gale  commences  from  the  northward,  gradually  changing 
through  west  to  south  and  southeast,  which  point  being  attained  its 
fury  forthwith  abates ;  or,  as  the  modern  mariner,  even  of  the  most 
slender  experience,  would  say,  cyclone  centers  travel  westward  to  the 
northward  of  the  West  India  Islands.  One  page  of  nature's  entranc- 
ing book  lay  wide  spread  before  the  observant  eyes  of  that  merchant 
shipmaster,  yet  he  failed  to  decipher  its  crabbed  characters  by  the 
imperfect  light  which  then  prevailed  in  the  world  of  science,  even 
though  he  quaintly  relates  that  storm  warnings  sent  to  more  western 
islands  from  Dominica  and  St.  Vincent,  ten  days  in  advance,  were 
generally  correct.  He  used  to  get  under  way  and  run  out  before  the 
northerly  gale  in  order  to  obtain  the  necessary  and  sufficient  searoom 
to  keep  clear  of  the  land  when  the  wind  should  shift  to  southwest. 
Three  centuries  ago,  then,  seamen  were  well  aware  that  West  Indian 
hurricanes  are  whirlwinds  of  comparatively  insignificant  diameter 
but  awful  energy,  and  that  they  might  be  fallen  in  with  most  often 
from  July  to  September.  Little  if  anything,  however,  was  known  as 
to  their  direction  and  rate  of  travel.  The  full,  change,  and  quarters 
of  the  moon  were  considered  critical  periods,  especially  if  the  sun 
were  exceptionally  red,  the  stars  with  halos,  the  hills  unusually  free 
from  cloud  and  mist,  the  northwest  sky  black  and  foul,  or  the  sea 
smelling  more  strongly  than  its  want.  Franklin,  in  a  letter  dated  at. 
Philadelphia,  July  16,  1747,  wrote  that  "  the  air  is  in  violent  motion 
in  Virginia  before  it  moves  in  Connecticut,  and  in  Connecticut  before 
it  moves  at  Cape  Sable,"  thus  foreshadowing  the  result  arrived  at  by 
Redfield,  a  naval  architect  of  New  York,  to  whom  the  world  is  deeply 
indebted  for  the  very  first  reliable  enunciation  of  the  law  of  storms. 
He  gathered  together  ships'  log  books,  laid  down  the  data  thus  obtained 
in  their  respective  geographical  positions  on  simple  synoptic  charts, 


FORECASTING    OF    OCEAN    STORMS.  153 

and  after  several  years  of  patient  inquiry  promulgated  his  views  about 
1831. 

After  the  lapse  of  more  than  three  score  years  this  dauntless  worker 
in  the  thorny  path  of  unendowed  scientific  weather  research  still 
stands  head  and  shoulders  above  all  comers,  save  Maury,  who  has 
never  been  equaled  as  a  passage  shortener  for  sailing  ships.  Neither 
the  masterly  deductions  of  Redfield  nor  his  well-devised  methods  of 
discussion  have  been  improved  upon,  except  in  unimportant  details. 
He  demonstrated  that  North  Atlantic  cyclones  have  their  birth  place 
eastward  of  the  West  Indies ;  that  their  diameters  measure  90  miles 
and  upward ;  that  the  wind  force  increases  as  the  center  is  ap- 
proached ;  that  the  rate  of  travel  is  from  10  to  30  miles  an  hour 
along  a  parabolic  trajectory  having  its  vertex,  or  point  of  recurva- 
ture,  near  the  American  coast  in  about  N.  30°;  that  the  changes  in 
wind  directions  experienced  by  ships  as  a  cyclone  passes  over  vary 
according  to  their  positions  with  respect  to  its  center;  and  suggested 
that  a  cyclone  whirled  round  a  cylindrical  axis  which  might  be  ver- 
tical or  inclined,  and,  perchance,  staggering  on  its  course  afflicted 
with  a  kind  of  nutation,  thus  causing  the  violent  gusts  and  interven- 
ing lulls  met  with  in  the  vicinity  of  the  center.  There  is  nothing 
new  in  the  much-vaunted  indraft  theory  of  later  writers,  inasmuch 
as  Redfield  explicitly  stated  that  he  merely  adopted  the  circular  form 
of  diagram  for  convenience  sake.  He  deemed  the  circle  good  enough 
to  show  the  fallacy  of  the  straight-line  theory  of  his  fime,  but  was 
not  able  to  conceive  that  a  storm  whirl  was  purely  circular,  and  had 
not  any  doubt  whatever  that  in  different  quadrants  of  the  same  storm 
might  be  experienced  any  wind  from  rotatory  to  rectilinear.  I  shall 
later  on  try  to  indicate  that  this  is  precisely  the  position  to-day. 
Redfield  happily  conjectured  that  storms  of  south  latitude  rotated  in 
an  exactly  opposite  direction  to  those  north  of  the  equator.  In  the 
old  sailing-ship  days,  when  passages  were  reckoned  by  months,  not  by 
minutes,  British  army  officers  had  much  sea  experience,  and  sailo*rs 
should  be  thankful  that  some  of  them  observed  and  discussed  the 
phenomena  of  ocean  storms.  Lieut.  Col.  Reid,  R.  E.,  confirmed  Red- 
field's  views  in  every  particular ;  Dr.  Thom,  of  the  Eighty-sixth  Reg- 
iment, came  to  a  like  conclusion ;  and  Piddington,  of  Calcutta,  put 
the  finishing  touches  to  the  law  of  storms  by  the  publication  of  his 
seaman-like  work,  which  is  bad  to  beat  even  now.  Over  fifty  years 
ago  it  was  shown  that  a  single  storm  may  split  up  into  two  or  more, 
and  conversely;  that  theVinds  in  a  cyclone  may  be  somewhat  in- 
curved; that  ships  under  the  influence  of  one  should  choose  the 
coming-up  tack;  and  the  storm  tracks  in  the  several  seas  were  well 
indicated.  Rules  for  storm  sailing  were  made  public  which  still 
obtain,  with  slight  modifications.  In  1849  Capt.  Andrews,  com- 
mander of  a  British  royal  mail  steamship,  impressed  upon  Col.  Reid 


154  CHICAGO    METEOROLOGICAL    CONGRESS. 

that  a  ship  would  sail  away  from  the  center  by  keeping  the  wind  on 
the  starboard  quarter  in  the  northern  hemisphere  and  on  the  port 
quarter  in  the  southern  hemisphere ;  provided,  she  would  steer  satis- 
factorily, and  not  broach  to,  a  fact  only  knoAvn  to  those  conversant 
with  her  sailing  qualities.  In  1872  Capt.  Wales,  harbor  master  at 
Mauritius,  appears  to  have  arrived  independently  at  a  similar  rule, 
and  this  maneuver  is  now  given  in  the  text  books.  It  is  to  Pidding- 
ton  that  we  owe  the  term  cyclone,  as  applied  to  revolving  storms, 
which  he  derived  from  xux/*/? ;  not  as  some  assert  as  afl&rming  a  true 
circle,  ])ut  merely  a  closed  curve,  for  in  the  Greek  that  word  represents 
among  other  things  the  coil  of  a  snake.  There  is  a  serious  difficulty 
in  the  way  of  understanding  exactly  what  Piddington  and  his  con- 
temporaries meant  by  "  incurving  spirals  "  and  "  cycloidal  "  wind 
systems. 

Modern  weather  workers  have  introduced  so  many  tantalizing  ex- 
ceptions to  the  law  of  storms  that  a  seaman  aware  of  them  would  be 
bewildered.  A  ship  at  sea,  in  a  cyclone,  is  not  a  fixed  observatory. 
Hence,  if  this  fact  be  ignored,  it  follows  that  arithmetical  exercises 
relative  to  the  angle  of  indraft  will  prove  exasperatingly  misleading. 
For  practical  purposes  the  circular  theory  is  not  more  uncertain  than 
any  other.  Blanford  asserted  that  a  cyclone  center  may  be  from  1  to 
5  points  before  the  port  beam  when  running  with  the  wind  right  aft 
in  the  Bay  of  Bengal ;  F.  Chambers  concludes  that  the  indraft  varies 
from  point  to  point  around  the  whirl,  increasing  from  zero  to  35°  as 
the  observer  recedes  from  the  storm  center ;  Capt.  Toynbee  found  that 
the  indraft  increases  as  the  center  is  approached  and  is  more  marked 
in  front  of  the  storm;  Capt.  Whall  is  firmly  convinced  that  with  a 
good  offing  the  wind  blows  directly  for  the  storm  center  in  the  rear ; 
Ferrel  proved  mathematically  that  indraft  varies  not  only  with  the 
distance  from  the  center,  but  also  with  the  latitude.  Many  other  ex- 
amples might  easily  be  given  of  conflicting  estimates  for  finding  the 
bearing  of  a  storm  center ;  but  enough  has  said  to  show  that  the 
problem  is.  so  far,  an  indeterminate  one  in  a  great  measure.  Even 
the  term  center  has  not  been  satisfactorily  defined.  Granted  that 
on  synchronous  charts  the  shape  of  a  cyclonic  disturbance  is  ellip- 
tical, with  the  major  axis  in  the  direction  of  travel,  then  is  the 
so-called  center  a  physical  point  or  an  area  at  one  or  other  of  the 
foci,  or  at  the  intersection  of  the  axes?  Occasionally  a  cyclone  ex- 
tends right  across  the  North  Atlantic  from  America  to  Europe,  and 
the  question  arises  as  to  the  bearing  of  ttie  center  of  such  a  system 
at  positions  along  the  closed  curve.  Abercromby  does  not  help  me 
to  form  any  definite  conclusion  when  he  says  that  the  center  of  a 
cyclone  is  displaced  toward  one  side  of  the  oval  and  may  move  from 
one  side  to  the  other !  Yet  the  center  is  the  first  requisite  in  fore- 
casting a  storm.  Comment  is  superfluous  from  a  nautical  point  of 
view. 


FORECASTING  OF  OCEAN  STORMS.  165 

The  average  tracks  of  storms  have  been  approximately  known  for 
many  years,  but  even  a  cursory  glance  at  the  1892  North  Atlantic 
Pilot  Charts,  published  by  the  U.  S.  Hydrographic  Office,  shows  that 
complicated  and  unexpected  divergences  from  the  usual  routes  occur 
at  times.  Similar  instances  are  also  noticeable  in  the  erratic  be- 
havior of  storms  over  other  oceans  which  would  upset  the  best  laid 
plans  of  experienced  storm  forecasters.  The  storm  tracks  of  1883, 
determined  by  the  U.  S.  Signal  Service,  clearly  indicate  that  the  route 
most  affected  by  Atlantic  cyclones  runs  from  a  position  south  of 
Newfoundland  to  the  north  of  Scotland.  They  drift  eastward  directly 
along  the  track  of  the  Gulf  Stream.  Some,  how^ever,  which  start  well, 
either  die  out  altogether  or  proceed  due  north  in  mid  Atlantic.  Others 
form  closed  curves  and  defy  prediction.  In  March  one  apparently 
broke  up  into  two  distinct  cyclones,  one  of  which  made  the  Bay  of 
Biscay,  and  the  other  Valentia,  on  the  west  coast  of  Ireland.  In 
April  one  which  had  reached  N.  50°,  W  25°,  broke  off  to  southeast, 
east,  and  northeast,  eventually  passing  over  Brest  instead  of  Aberdeen, 
as  a  well-regulated  cyclone  would  have  done.  Another  in  mid-ocean 
traveled  east,  north,  southwest,  south,  and  northeast.  In  November 
a  cyclone  moved  eastward  to  the  southward  of  the  Azores  for  three 
days ;  and  another  in  December  moving  southeast  in  N.  50°,  W.  37°, 
turned  east  and  northeast  to  N.  50°,  W.  32°,  thence  north,  west,  south, 
and  southeast  to  N.  48°,  W.  32°,  where  it  apparently  joined  forces 
with  another,  which,  three  days  later  had  followed  it  over  Halifax, 
N.  S.  The  rate  of  travel  is  also  very  variable.  One  of  the  above- 
mentioned  storms  moved  over  20°  of  longitude  during  each  of  two 
consecutive  days,  but  only  10°  during  the  following  forty-eight  hours. 
Occasionally  a  rapidly-moving  storm  comes  to  a  halt  for  a  few  days 
and  then  takes  up  the  running  again  like  a  giant  refreshed.  Mr. 
R.  H.  Scott,  and  others,  have  referred  to  this  fact  at  various  times. 
Hence,  there  is  little  cause  for  surprise  that  the  public  -  spirited 
attempt  of  the  New  York  Herald  to  forecast  storms  bound  across  the 
North  Atlantic  was  not  so  successful  as  it  deserved  to  be.  The 
average  direction  and  rate  of  travel .  for  cyclones  over  a  given  ocean 
avail  but  little  when  tracks  are  not  infrequently  looped  and  the 
onward  motion  anything  up  to  70  miles  an  hour. 

The  electric  telegraph  has  done  much  to  make  easier  the  lot  of  a 
storm  forecaster  on  shore,  working  in  a  snug  room  far  distant  from 
an  approaching  disturbance.  Redfield,  in  1847,  seems  to  have  sug- 
gested that  this  means  of  conveying  storm  intelligence  between  one 
place  and  another  would  be  useful.  The  late  Admiral  Fitzroy  may, 
ho\vever,  be  regarded  as  the  pioneer  of  storm  forecasting  based  upon 
actual  observations  transmitted  by  ware  from  remote  stations  to  a 
central  weather  office,  to  be  dealt  with  there  and  warnings  issued  to 
the   seaports  when  necessary.     His   predictions  were  not  always  in 


156  CHICAGO    METEOROLOGICAL   CONGRESS. 

agreement  with  the  results,  but  it  must  not  be  forgotten  that  they  were 
tentative,  and  even  now  certainty  is  denied.  The  idea  of  warning  the 
coasts  of  Europe  by  telegram  from  ships  anchored  in  the  ocean  to 
westward  has  frequently  been  mooted,  and  warnings  from  North 
America  are,  and  have  been  in  favor.  The  Anglo-American  Telegraph 
Company  sent  messages  without  charge  from  Heart's  Content,  New- 
foundland, to  England,  but  the  place  of  observation  was  unsuital^le 
for  the  purpose  and  they  were  discontinued  in  1871.  James  Gordon 
Bennett  obtained  better  results  in  a  similar  way  at  his  own  expense, 
and  France  has  not  lost  all  faith  in  this  method,  as  she  still  receives 
information  from  Washington  of  storms  encountered  by  steamships 
bound  westward.  The  U.  S.  Hydrographic  Office  is  in  possession  of 
many  records  of  the  weather  experienced  by  the  Atlantic  "  grey- 
hounds," and  an  examination  of  these  passages  would  perchance  de- 
termine whether,  and  how  often,  a  Campania  or  a  Paris  might  give 
reliable  storm  warnings  at  either  end  of  the  journey,  provided  every 
effort  were  made  to  obtain  such  information  immediately  upon  arrival 
at  Queenstown,  Southampton,  and  New  York.  Her  Majesty's  ship 
Brisk  anchored  for  six  weeks  at  the  entrance  to  the  English  Channel 
as  a  stationary  storm-warning  vessel,  but  she  proved  a  failure.  It 
may  be  that  those  responsible  did  not  have  their  hearts  in  the  work ; 
for  Capt.  ^Vharton,  R.  N.,  Hydrographer  to  the  British  Admiralty, 
has  said  that  anchoring  at  sea  is  not  such  a.  physical  impossibility  as 
some  shore  folk  believe.  Morse  thought  that  simple  automatic  regis- 
tering buoys  might  be  dotted  over  the  ocean,  and  Capt.  W.  Parker 
Snow  has  been  bold  enough  to  indicate  a  cordon  of  ships  at  intervals 
of  500  miles  anchored  between  North  America  and  Europe,  in  elec- 
trical communication  with  each  other  and  with  the  land. 

If  storm  warning  be  worth  doing  at  all  it  is  worth  doing  well,  and 
money  should  no  more  be  begrudged  in  promoting  the  safety  of  life 
than  it  is  to  the  invention  of  means  for  the  more  expeditious  destruc- 
tion thereof.  There  should  be  educated  observers,  nautical  men  by 
preference,  familiar  with  weather  indications  at  their  several  stations, 
at  Martinique,  St.  Thomas,  Habana,  Nantucket,  Cape  Sable,  Cape 
Race,  Valentia,  Iceland,  Bermuda,  Madeira,  and  Flores,  all  in  com- 
munication by  submarine  cable  with  the  United  States  and  Europe. 
Science  is  catholic,  and  each  maritime  nation  might  be  required  to 
support  this  international  system  of  storm  warning.  If  this  be  im- 
possible, then  I  would  suggest  that  synchronous  charts  for  the  whole 
globe  be  undertaken,  on  which  would  be  carefully  laid  down  the 
requisite  information,  but  free  from  an  undue  striving  after  artistic 
elfect  which  adds  nothing  to  their  utility  though  much  to  their  cost. 
They  should  be  international  in  every  way,  and,  after  the  weather 
workers  of  each  nation  have  drawn  isobars,  etc.,  on  precisely  the  same 
data,  a  critical  comparison  should  be  carried  out  by  a  truly  repre- 


FORECASTING  OF  OCEAN  STORMS.  157 

eentative  conference ;  the  best  sets  chosen,  not  as  specimens  of  geo- 
metrical drawing,  but  as  representations  of  fact,  and  deductions  for 
storm  warnings  made  therefrom.  An  accurate  acquaintance  svith  the 
conditions  that  prevail  twenty-four  hours,  or  more,  previous  to  the 
passage  of  an  awful  cyclone  over  an  exposed  roadstead  or  coast  line 
may  be  of  infinitely  greater  value  to  navigators  and  shore  forecasters 
than  the  most  detailed  climatological  treatise  based  upon  insufficient 
data.  Similarly,  points  of  vantage  in  other  oceans  should  be  coupled 
up  with  the  central  forecasting  establishments  in  the  vicinity  and 
provided  with  competent  observers. 

A  storm  warning  to  be  of  use  to  the  shipping  Community,  whom  it 
principally  concerns,  must  fulfill  several  conditions.  It  must  be  of 
such  a  nature  as  to  be  easily  understood  by  navigators  in  ships  of  all 
nations;  it  must  really  be  a  notification  that  a  gale  will  blow  from  a 
specified  direction  and  proceed  along  a  clearly-defined  track,  and  not 
merely  a  record  of  present  weather,  or  a  false  alarm ;  and  it  should 
be  sufficiently  reliable  and  explanatory  to  assist  seafarers  in  arriving 
at  a  proper  appreciation  of  weather  to  seaward.  In  fact,  off  Ushant 
and  Finisterre,  for  example,  a  ship  might  be  informed  not  only  as  to 
the  storm  expected  at  either  place,  but  also  farther  north  or  south,  as 
necessary.  The  storm  signals  should  be  clear  enough  to  do  away  with 
any  necessity  for  reference  to  telegrams  on  view  in  the  vicinity.  It 
is  not  sufficient  that  a  navigator  be  only  informed  whether  the  north- 
ern or  southern  portion  of  a  cyclone  is  expected  to  pass  over  the  sta- 
tion displaying  the  signals.  The  question  as  to  the  best  form  in 
which  warnings  should  be  made  is  a  strictly  nautical  one,  and  might 
be  decided  by  a  committee  of  representative  officers  of  war  ships  and 
merchantmen.  The  international  code  of  signals  might  be  utilized, 
notwithstanding  the  disadvantage  of  flags  in  a  calm,  or  blown  out 
directly  to  or  from  an  observer.  They  are,  however,  probably  prefer- 
able to  shapes,  such  as  cones  or  rectangles ;  and  semaphores  find  many 
admirers.  Light-ships  in  connection  with  the  shore  by  submarine 
cable,  signal  stations,  life-saving  stations,  and  lighthouses  should  all 
be  pressed  into  the  service  of  warning  for  ocean  storms  both  by  day 
and  by  night. 

I  have,  doubtless,  tried  your  patience  considerably,  yet  the  magni- 
tude and  importance  of  forecasting  ocean  storms  would  demand  for 
a  due  appreciation  thereof  a  far  more  extended  scope.  If  this  paper 
will  but  awaken  navigators  of  the  world's  war  ships  and  mercantile 
marine  to  the  desirability  of  making  their  voices  heard  more  fre- 
quently with  no  uncertain  sound  on  points  connected  with  their  v.-ell 
being,  I  shall  not  have  encroached  upon  your  time  and  attention  in 
vain.  I  can  not  do  better  than  close  this  necessarily  imperfect  sketch 
by  quoting  the  words  of  Capt.  D.  Wilson  Barker,  R.  N.  R.,  who  has 
devoted  himself  to  marine  weather  work,  especially  in  the  direction 


168  CHICAGO    METEOROLOGICAL   CONGRESS. 

of  cloud  observations :  "  Probably  no  prognostic  is  so  valuable  to  a 
sailor  as  that  afforded  by  clouds,  particularly  those  of  the  cirrus 
formation ;  and  while  their  value  as  prognostics  has  been  recognized 
from  the  most  ancient  times,  it  is  only  rarely  cultivated,  and  yet  I 
have  no  hesitation  in  saying  that  there  is  no  weather  warning  for  an 
isolated  observer  that  can  in  any  way  compare  with  them."  My  old 
master,  Capt.  Henry  Toynbee,  whose  name  is  a  household  word  among 
officers  of  the  British  mercantile  marine,  Ensign  Everett  Hayden, 
U.  S.  Navy,  and  other  observers  have  also  mentioned  the  same  fact  for 
the  benefit  of  navigators.  Capt.  A.  G.  Froud,  R.  N.  R.,  has  just  sent 
me  an  interesting  letter  of  Vice -Consul  Ramsden,  at  Santiago  de 
Cuba,  explaining  the  method  of  Padre  Vines  at  Habana,  a  well-known 
authority  on  West  Indian  hurricanes,  and  stating  that  in  Cuba  cirrus 
gives  the  first  indication  of  the  position  of  a  hurricane,  and  that  the 
clouds  "enable  one  to  say  whether  the  low  barometer  is  due  to  a  cir- 
cular storm  or  not."  Nevertheless,  it  must  not  be  forgotten  that 
cloud  observation  requires  careful  training,  and  schools  for  teaching 
the  elements  of  weather  work  are  conspicuous  by  their  absence  on 
this  side  of  the  North  Atlantic.  Manj^  leagues  aAvay,  I  can  not  but 
await  your  reception  of  my  paper  with  some  trepidation,  mindful, 
however,  of  the  fact  that  the  man  of  science  "  loveth  truth  more  than 
his  theory,"  and  that  the  subject  is  of  itself  far  more  important  than 
the  manner  of  explanation. 


2.— THE  CREATION  OF  METEOROLOGICAL  OBSERVATORIES  ON 
ISLANDS  CONNECTED  BY  CABLE  WITH  A  CONTINENT. 

Al-BKKT,     PlUNCE    OF    MoNACMI. 

During  the  long  periods  of  time  spent  on  the  North  Atlantic,  on 
board  of  my  schooner,  VHirondclle.  devoted  to  investigations  touching 
oceanography,  and  after  a  careful  study  of  the  important  labors  of 
American  oceanographers  and  meteorologists,  I  remain  convinced  of 
the  utility  attached  to  the  creation,  upon  the  scattered  islands  be- 
tween Europe  and  America,  of  posts  of  observation  daily  reporting 
the  state  of  the  atmosphere  to  a  central  bureau,  as  soon  as  they  shall 
be  in  direct  communication  by  means  of  telegraphic  cables  with 
either  of  these  two  continents. 

By  means  of  the  meteorological  observatories  now  on  the  continent 
we  are  permitted  to  forecast,  in  a  general  manner,  the  approach  of 
certain  tempests.  But  what  results  would  be  obtained  if  those  per- 
turbations were  studied  upon  the  very  spot  where  formed,  inasmuch 
as  the  surface  of  the  waters  gives  origin  to  most  of  the  phenomena 
which  break  the  equilibrium  of  the  atmosphere. 

Meteorological  observatories  on  the  ocean,  allowing  us  to  trace  in  a 


OBSERVATORIES    ON    ISLANDS.  169 

regular  manner  the  mutation  of  minima  and  maxima,  the  variations 
of  the  temperature  and  winds,  would  afford  the  means  of  distinguish- 
ing the  principal  whirlwinds  and  the  secondary  depressions,  and 
enable  us  to  trace  the  zone  of  influence  of  each  of  them. 

The  following  is  my  scheme  comprehending,  in  its  broad  lines,  the 
organization  of  North  Atlantic  observatories : 

The  expenditures  for  the  creation  and  keeping  up  of  these  estab- 
lishments should  be  supported  in  common  by  the  governments  of 
Europe  and  that  of  the  United  States.  Individual  donations,  besides, 
should  be  accepted. 

The  points  which  I  consider  as  most  important  for  the  meteoro- 
logical observatories  of  the  North  Atlantic  are  the  Cape  Verde 
Islands,  the  Azores,  and  the  Bermudas. 

The  Cape  Verde  Islands  are  situated  iif  a  region  in  which,  accord- 
ing to  the  Pilot  Chart,  many  storms  originate,  thence  going  to 
ravage  the  West  Indies  and  the  coasts  of  the  United  States.  Those 
islands  are,  at  the  same  time,  situated  along  the  outer  border  of  the 
circular  movement  of  the  North  Atlantic  waters,  of  which  my 
researches  upon  the  currents  have  shown  the  existence  and  the 
course. 

The  Azores  are  situated  near  the  center  of  this  circulation,  on 
which  account  they  deserve  special  attention,  forasmuch  as  an  inter- 
esting coalescence  occurs  between  that  center  and  the  center  of  the 
area  of  high  oceanic  pressures  when  the  maximum  is  bearing  west- 
wardly  to  coincide  with  that  of  the  Bermudas. 

The  Bermudas  are  situated  near  the  western  border  of  the  circula- 
tion of  the  waters,  not  far  from  the  Gulf  of  Mexico,  which  plays  an 
important  part  in  oceanic  meteorology ;  moreover,  they  are  under 
the  influence  of  the  Gulf  Stream. 

With  these  three  points  at  our  command  an  efficient  supervision 
could  be  exercised  over  the  North  Atlantic.  So  much  the  more  as  at 
the  Cape  Verde  Islands  and  at  the  Azores  the  height  of  the  moun- 
tains (2,974  m.  and  2,321  m.)  would  permit  complete  observations 
to  be  made  by  means  of  neighboring  posts  for  the  observation  of  the 
upper  regions  of  the  atmosphere.  But  such  supplementary  observa- 
tions would,  for  the  present,  be  of  secondary  importance  in  the  pre- 
vision of  weather,  inasmuch  as  the  inquiry  thus  far  made  into  the 
materials  collected  at  the  observatory  of  Ben  Nevis  shows  that  ob- 
servation of  the  inferior  layers  is  the  most  advantageous  to  such  a 
prevision. 

It  will  oftentimes  happen  that  the  observatories,  if  placed  at  St. 
Vincent  for  the  Cape  Verde  Islands,  and  at  San  Miguel  for  the  Azores, 
and  on  the  principal  island  for  the  Bermudas,  will  be  in  a  position, 
by  ships  putting  into  port,  to  add  to  the  local  observations,  observa- 
tions made  at  sea  one  or  two  days  previously.     Thus,  we  should  pos- 


160  CHICAGO    METEOROLOGICAL    CONGRESS. 

Bess,  at  a  given  time,  a  small  network  of  observations  covering  a  sur^ 
face  of  several  degrees. 

For  a  long  time  I  have  been  meditating  upon  the  programme  of 
which  the  broad  lines  are  indicated  above.  But  ere  entering  into  its 
execution  I  must  wait  until  the  center  of  observations,  the  most 
interesting  for  Europe,  the  group  of  Azores,  shall  be  connected  with 
the  continent  by  a  cable.  Judging  from  the  actual  agitation  about 
that  undertaking,  it  is  allowed  to  hope  that  the  laying  of  the  cable  is 
a  mere  question  of  time ;  the  moment  seems,  therefore,  opportune  to 
prepare  the  desired  scheme. 

I  thought  it  useful  to  bring  before  the  intellectual  assembly  which 
meets  this  day  in  America  (scientific  representatives  of  the  whole 
world  bestowing  a  new  impetus  upon  the  activity  of  human  intellect) 
this  question  of  oceanic  observatories  which,  by  the  manifold  services 
they  should  return,  would  soon  be  multiplied  on  the  surface  of  the 
globe. 

This  question  was  brought  by  me  last  year  before  the  Academy  of 
Sciences  of  Paris,  and  before  the  British  Association  at  its  session  in 
Edinburgh  ;  on  both  occasions  the  meteorologists  and  oceanographers 
of  Europe  agreed  completely  upon  the  desirability  of  establishing  the 
aforesaid  observatories.  I  am  convinced  that  the  American  savants, 
always  practical  and  stout  hearted  concerning  enterprises  of  great 
scope,  will  likewise  join  their  efforts  to  mine  in  hastening  the  execu- 
tion of  my  plans.  Is  North  America  not  interested  in  the  same  de- 
gree as  Europe  in  the  possession  of  advanced  information  of  atmos- 
pheric perturbations  originating  upon  the  ocean,  and  which  exercise 
so  considerable  an  influence  upon  the  meteorology  of  both  continents? 
Unquestionably  it  is  a  great  progress  wanting  realization  for  the  ad- 
vance of  modern  civilization. 

Again,  what  will  be,  for  powerful  nations,  the  pecuniary  sacrifices 
involved  in  the  aforesaid  scheme  compared  to  the  ruinous  prepara- 
tions for  war  \yhich  seem  rather  contemplated  to  thrust  back  the 
human  race  into  barbarism. 

At  least  when  these  edifices  shall  arise  in  the  midst  of  the  seas,  far 
from  the  turmoil  of  politics  and  war,  will  it  not  be  a  legitimate  com- 
pensation to  wise  men,  thoughtful  of  labor,  progress,  and  peace,  and 
justly  alarmed  in  viewing  people  armed  for  destruction?  Most  cer- 
tainly so,  and  the  good  parole  of  science  announcing  new  discoveries 
shall  attenuate  the  voice  of  cannons. 

I  come  with  so  much  the  more  joy  to  lay  before  you  my  projects, 
as  I  am  certain  to  find  with  you  a  similar  thought,  for  you  are  the 
descendants  of  the  sturdj'-  men  who  fought  of  yore  for  life  and  knowl- 
edge ;  you  are  already  the  men  of  the  future,  contemptuous  of  the 
vain  glory  of  conquests. 


THE   MARINE   NEPHOSCOPE.  161 

3.— THE  MARINE  NEPHOSOOPE  AND  ITS  USEFULNESS  TO 
THE  NAVIGATOR. 

Prof.  Cleveland  Abbe. 

The  object  of  the  marine  nephoscope  is  to  enable  the  navigator  to 
observe  the  motions  of  the  clouds,  either  upper  or  lower,  as  easily  as 
he  observes  the  winds.  He  may  not  only  deduce  therefrom  the  loca- 
tion of  a  storm  center  at  any  moment,  which  knowledge  he  needs  for 
his  own  safety,  but  may  also  put  on  record  the  data  by  means  of 
which  other  students  can  determine  the  actual  heights  and  motions 
of  the  clouds  which  will  be  needed  in  the  further  advance  that  me- 
teorology is  sure  to  make. 

I  would  not  assert  that  we  have  as  yet  all  the  data  needed  by  which 
the  navigator  can  quickly  determine  the  distance  and  direction  of  the 
storm  center  at  any  moment ;  but  we  have  here  the  long-needed  in- 
strument and  I  wiW  indicate  the  method  of  using  it,  and  the  further 
general  process  of  reasoning,  in  hopes  that  this  may  attract  the  at- 
tention of  the  navigator  to  the  practical  value  of  the  marine  nepho- 
scope. The  instrument  and  its  use  are  so  simple,  and  the  interest 
that  attaches  to  the  subject  is  so  great,  that  it  is  important  that 
navigators  in  both  naval  and  merchant  marine  should  learn  its  use 
and  record  the  motions  of  the  clouds  as  regularly  as  they  do  other 
meteorological  items. 

In  the  gradual  development  of  our  knowledge  of  storms  we  have 
historically  passed  through  many  stages,  e.g.,  (1)  the  study  of  the 
winds;  (2)  the  study  of  individual,  local,  or  isolated  barometric  de- 
pressions, namely,  the  simple  rising  and  falling  of  an  individual 
barometer;  (3)  the  study  of  the  differences  or  departures  of  observed 
barometers  from  the  normal  or  average  readings  of  the  same  instru- 
ments at  the  same  altitude  above  sea  level ;  (4)  the  study  of  the  rel- 
ative pressures  at  many  stations  all  reduced  to  sea  level,  and  of  late 
years  also  reduced  to  standard  gravity ;  ( 5 )  the  study  of  the  de- 
partures of  the  individual  readings,  reduced  to  sea  level,  from  the 
average  pressure  proper  to  the  small  circle  of  latitude  round  the  whole 
globe.  Incited  by  the  investigations  of  Guldberg  and  Mohn,  of  Ferrel 
and  other  leaders,  meteorologists  have  of  late  years  paid  special  atten- 
tion to  the  angle  between  the  wind  and  the  isobar,  but  isobars  can 
not  be  drawn  or  used  by  the  mariner  at  sea,  neither  should  the  isobar 
be  considered  to  the  exclusion  of  the  effects  of  temperature  and  mois- 
ture in  altering  the  density  of  the  air ;  therefore,  both  for  practical 
and  theoretical  reasons,  the  navigator  must  confine  his  attention  to 
the  angle  between  the  direction  toward  which  the  wind  is  moving  at 
the  observer's  station  and  the  direction  in  which  the  storm  center 
lies  with  reference  to  his  station. 

By  storm  center  we  shall  in  this  paper  mean  the  central  point 
11 


162 


CHICAGO    METEOROLOGICAL    CONGRESS. 


about  which  rotates  a  system  of  whirling  winds.     We  must  distin- 
guish between  this  center  of  winds  and  the  barometric  storm  center,! 
which  latter  is  defined  as  the  center  of  the  smallest  isobaric  circle  or] 
ellipse.     This  latter  is  the  storm  center  of  modern  dynamic  meteor- 
ology ;  the  former  is  the  storm  center  of  the  mariner  and  of  the  older] 
cyclonologists.     These  centers  are  often  identical,  but  not  necessarily 
always  so.     Mechanical  principles   have   of   late   years   required  us! 
to  study  the  relations  of  the  winds  to  isobars  and  isabnormals,  but 
having  done  this  we  must  now  return  to  the  older  problem  and  for 
the  use  of  the  mariner,  must  apply  our  increased  knowledge  to  the 
study  of  the  simple  geometrical  problem  that  he  has  to  do  with, 
namely,  the  relation  between  the  movement  of  the  wind  and  the  bear- 
ing and  distance  of  the  storm  center. 

As  the  direction  of  the  wind  is  so  minutely  observed  by  navigators! 
who  understand  how  to  determine  its  true  direction,  notwithstanding 
the  motion  of  the  vessel  on  which  they  are  sailing*  it  should  be  easily] 
possible  by  the  accumulation  of  weather  maps  to  determine  the  di- 
rection and  incurvature  of  the  wind  on  all  sides  of  the  storm  centers] 
at  sea.  Therefore,  up  to  the  present  time  the  navigator  has  relied  | 
upon  the  wind  and  its  changes  to  indicate  to  him  the  location  and 
movement  of  the  storm  center  that  he  wishes  to  avoid. 

The  progress  of  our  knowledge  of  the  motions  of  the  upper  and 
lower  currents  of  air  in  the  neighborhood  of  a  well-defined  hurricane 
center  has  made  it  apparent  that  we  may  improve  upon  the  old  rule 
of  the  earlier  cyclonologists  who  assumed  that  the  wind  blew  in  a 
circle  around  a  hurricane  center  and  who,  therefore,  stated  that  if  in 
the  northern  hemisphere  the  navigator  stand  with  his  back  to  the 
wind  he  will  have  the  center  on  his  left. hand. 

This  rule  was  always  recognized  as  rather  crude,  yet  for  a  long  time 
nothing  better  was  offered  for  the  use  of  mariners,  notwithstanding 
the  fact  that  the  charts  of  Redfield,  Espy,  Loomis,  Lloyd,  and  Lever- 
rier  all  showed  that  the  rule  is  not  a  law  of  nature.  The  fact  that 
the  winds  are  inclined  inward,  as  compared  with  the  path  required 
with  the  truly  circular  theory,  was  stated  very  emphatically  by  Red- 
field  in  1846,  and  he  adds  that  in  his  charts  of  storms  the  engraver 
had  sometimes  drawn  the  winds  in  accordance  with  the  old  theory, 
contrary  to  Redfield's  better  judgment.  He  states  that  the  average 
inclination  of  the  wind  to  the  circular  tangent  rarely  exceeds  two 
points  of  the  compass,  and  is  never  so  much  as  was  often  claimed  by 
Espy ;  but  it  seems  to  me  that  the  fact  should  not  be  lost  sight  of 
that  the  land  storms  studied  by  Espy  and  the  ocean  hurricanes  studied 
by  Redfield  are  two  modes  of  motion  in  the  atmosphere  that  are  often 
essentially  different  from  each  other. 

The  rules  for  locating  the  center  of  a  hurricane  and  for  determining 
the  direction  of  its  motion,  hitherto  used  by  navigators,  have  been 


THE    MARINE    NEPHOSCOPE.  163 

based  largely  upon  the  study  of  the  direction  of  the  wind,  but  this  is 
subject  to  considerable  local  irregularities  if  the  mariner  is  in  the 
neighborhood  of  any  land ;  moreover,  the  inclination  of  the  wind  to  the 
radius  from  the  storm  center  varies  largely  with  the  latitude  and  the 
position  with  regard  to  that  center.  Numerous  studies,  especially 
those  of  Broun,  Ley,  Hildebrandsson,  Ekholm,  and  Clayton,  have 
shown  that  the  movement  of  the  wind  is  subject  to  considerable  irregu- 
larity and  if  the  navigator  can  avail  himself  of  the  direction  of  mo- 
tion of  the  clouds  he  may  locate  the  storm  center  with  much  greater 
accuracy.  The  most  extensive  series  of  observations  of  upper  and 
lower  clouds  is  that  published  by  Broun  in  the  annual  volumes  of 
his  observations  at  Makerstoun,  Scotland,  for  1843-46,  which  form  a 
part  of  the  Transactions  of  the  Royal  Society  of  Edinburg.  As  the 
result  of  about  3,000  observations  Broun  found  that  the  lower  cumulus 
scud  is  inclined  outward  to  the  winds  by  14.5° ;  the  next  layer  above, 
or  cirro-stratus,  inclines  outward  22.8° ;  the  highest  layer  of  clouds, 
or  true  cirri,  is  inclined  outward  29.6°.  These  observations  were  for 
many  years  overlooked  until,  in  1871-72,  both  Clement  Ley  and  my- 
self, by  the  study  of  English  and  American  observations,  respectively, 
independently  announced  the  general  rule,  almost  in  the  words  that 
Broun  had  used  twenty-five  years  before,  that  as  we  ascend  in  the  at- 
mosphere the  angle  by  which  the  movement  of  a  given  layer  differs 
from  the  movement  of  the  lowest  wind  deviates  more  and  more  to  the 
right.  As  a  result  of  the  work  that  has  hitherto  been  done  on  this 
subject  I  think  we  may  for  the  present  adopt  the  general  rule  that 
between  the  winds  that  blow  spirally  inward  and  the  upper  clouds  that 
.blow  spirally  outward  there  is  an  intermediate  layer  of  the  so-called 
lower  clouds  whose  motion  is  very  nearly  along  a  circular  arc  and 
that  the  mariner  may  more  safely  locate  his  storm  center  as  being  in 
a  line  perpendicular  to  the  motion  of  the  lower  clouds  rather  than  to 
rely  entirely  upon  the  surface  winds.  If  he  observe  the  angle  be- 
tween the  movements  of  the  wind  and  the  lower  clouds  and  again 
between  the  lower  and  the  upper  clouds,  he  has  a  further  means  of 
determining  even  the  distance  of  the  storm,  although  the  definite  rules 
for  so  doing  need  not  now  be  given. 

Assuming,  therefore,  that  the  storm  center  bears  at  right  angles  to 
the  direction  of  movement  of  lower  clouds  and  is  on  one's  right  hand 
when  he  faces  the  direction  from  which  these  clouds  are  coming,  it 
remains  only  to  show  how  to  use  the  nephoscope  in  order  to  obtain 
the  direction  of  cloud  movement. 

The  accompanying  diagrams  (Plate  vi)  present  both  a  horizontal 
projection  and  a  vertical  section  of  Ritchie's  Patent  Liquid  Compass, 
as  used  on  American  naval  vessels,  as  also  a  similar  projection  and 
vertical  section  of  my  marine  nephoscope.  The  compass  proper  may 
be  described  as  a  heavy  bowl  mounted  on  gimbals  and  so  adjusted  as 


164  CHICAGO    METEOROLOGICAL    CONGRESS. 

to  its  axis  of  gyration  that  its  time  of  vibration  is  rather  long,  namely, 
about  one-half  second.  The  lower  half  of  the  bowl  is  ballasted,  and 
its  upper  half  constitutes  a  closed  receptacle  full  of  liquid,  bounded 
by  the  circular  plate  of  glass.  Within  the  liquid  floats  the  compass 
card  and  needles ;  the  compass  card  shows  not  only  the  thirty-two 
quarter  points,  but  also  every  degree  of  azimuth.  The  observer  look- 
ing down  upon  the  plate-glass  top  sees  the  compass  card,  which  is 
just  below  it,  and  also  the  lubber  line,  FA,  as  marked  on  the  brass 
rim.  As  the  vessel  rolls  or  pitches  the  compass  card  preserves  its 
horizontal  position  fairly  well  up  to  a  limiting  roll  of  about  thirty 
degrees.  In  the  standard  compass  of  the  U.  S.  Navy  the  upper  edge 
or  flange  of  the  compass  bowl,  EE,  is  neatly  turned  to  an  exact  circle 
concentric  with  the  pivot  and  about  9^  inches  in  diameter.  This  is 
for  the  purpose  of  setting  thereon,  at  any  moment,  the  alidade  and 
sights  for  observing  the  sun  and  stars,  or  otherwise  determining  the 
true  azimuth  and  the  magnetic  variations  and  deviations  at  any  time. 
Ordinarily,  this  apparatus  is  not  in  place  on  the  compass,  and,  there- 
fore, without  disturbing  the  regular  work  of  the  ship,  we  may  set  the 
nephoscope  on  the  compass  in  place  of  the  astronomical  apparatus. 
The  thin  circular  vertical  flange  of  the  nephoscope  is  shown  in  sec- 
tion RR,  and  it  fits  snugly  over  EE.  The  nephoscope  consists  essen- 
tially of  this  circular  flange  RR,  whose  upper  horizontal  surface  is 
the  ring  on  which  appear  the  graduations  for  every  five  degrees,  num- 
bered from  0  around  to  360  in  the  direction  in  which  azimuths  are 
ordinarily  measured.  In  order  to  revolve  this  ring  horizontally,  two 
small  handles,  PQ,  are  provided.  Within  the  graduated  ring  the  cir- 
cular area  is  covered  by  a  single  plate  of  thin  mirror  glass  of  excel- 
lent quality,  silvered  on  the  lower  side.  But  as  it  is  necessary  to  look 
through  at  the  compass  card  below,  the  silvering  has  been  removed 
in  a  broad  circular  band ;  there  is  also  a  smaller  circle  of  half  its 
size,  as  shown  by  the  heavy  black  line ;  the  outer  and  inner  bounda- 
ries of  these  circles  are  made  quite  exactly  smooth  and  concentric 
with  the  center  of  the  small  black  spot,  C,  which  is  immediately  over 
the  compass  pivot. 

When  this  silvered  mirror  is  in  place  upon  the  compass  it  repre- 
sents a  horizontal  plane,  and  it  preserves  its  horizontality  with 
remarkable  persistence,  notwithstanding  the  ordinary  rolling  and 
pitching  of  the  vessel.  In  the  absence  of  any  convenient  method  of 
exact  measurement,  I  have  been  able  only  to  estimate  that,  in  the 
case  of  the  compass  used  by  me  on  board  of  the  U.  S.  S.  Pensacola, 
the  inclination  of  the  mirror  plane  to  the  horizon  was  rarely  more 
than  two  degrees,  and  to  this  extent,  therefore,  an  uncertainty  is 
introduced  into  all  our  measurements ;  but,  as  the  inclination  is  per- 
petually oscillating  from  positive  to  negative,  we  have,  therefore,  only 
to  take  the  average  of  a  few  observations  in  order  to  obtain  results 


EPHOSCOPE, 


Abbe. 


Horizontal  Projection  of  Compass. 


MARINE    NEPHOSCOPE, 


Section  on  line  ab. 


Horizontal  Projection  of  Nephoscope. 


Horiznnl.i!  Pmiectiun  of  Compass 


i 


THE    MARINE    NEPHOSCOPE.  165 

that  are  appreciably  free  from  this  source  of  error.  The  observer 
must,  however,  be  careful  to  keep  the  compass  in  such  adjustment 
that  the  bowl  shall  not  have  any  constant  error  in  this  respect;  of 
course  this  same  adjustment  is  also  ifecessary  in  connection  with  the 
observation  of  the  the  sun  or  stars. 

In  so  far  as  the  mirror  is  horizontal,  therefore,  a  line  drawn  per- 
pendicular to  it  at  its  center  is  an  approximate  realization  of  a 
standard  vertical  line  on  shipboard,  and  our  object  now  is  to  deter- 
mine the  motion  of  the  clouds  with  reference  to  the  zenith  and  hori- 
zon of  this  mirror.  When  the  observer  looks  into  the  mirror  he  sees 
reflected  therein  not  only  the  masts,  and  rigging,  and  pennants,  but 
the  clouds,  and  even  the  sun,  moon,  and  stars.  The  apparatus  is  a 
simple,  crude,  but  convenient  altitude  and  azimuth  instrument,  and 
with  it  we  can  perform  all  the  operations  of  determining  altitudes, 
latitude,  time,  longitude,  and  azimuth  with  a  very  surprising  degree 
of  accuracy.  I  have  many  times  had  occasion  to  set  up  this  nepho- 
scope  on  shore,  and,  besides  observing  the  clouds,  have  determined 
the  altitude  and  azimuth  of  the  sun  ;  the  probable  error  of  a  single 
measured  altitude  of  the  sui»or  moon  is  about  one-quarter  of  a  de- 
gree, and  could  be  made  still  smaller  by  appropriate  changes  in  the 
construction.  In  order  to  measure  the  apparent  altitude  and  azi- 
muth of  clouds  by  a  method  suifficiently  expeditious,  simple,  and 
accurate  for  use  at  sea  I  devised  the  hollow  tube  SS,  and  the  sliding 
rod  which  fits  within  it  with  friction,  and  which  carries  at  its  end 
the  small  knob,  K.  The  tube  has  a  motion  in  a  vertical  plane  about 
the  hinge,  S,  and  when  elevated  to  any  altitude  is  held  there  by  the 
friction  of  this  joint.  The  vertical  plane  through  the  tube,  the  knob, 
the  central  spot,  C,  and  the  hinge,  S,  corresponds  with  the  zero  of  the 
graduation  of  the  horizontal  rim.  The  numbering  of  the  degrees 
is  from  0  to  360.  The  knob  and  the  central  spot,  C,  have  the  same 
diameter  so  that  in  whatever  position  the  knob  may  be  placed  (by 
elevating  the  tube  and  sliding  the  rod  in  or  out)  the  observer  can 
bring  his  eye  to  such  a  position  that  he  will  see  the  knob  reflected  in 
the  mirror  and  exactly  covering  the  spot.  Let  us  suppose  that  the 
observer  has  done  this  and  that  he  also  sees  reflected,  at  C,  a  small 
bit  of  cloud  or  a  point  in  a  large  cloud,  then  if  he  continues  to  hold 
his  eye  in  such  a  position  that  K  always  falls  upon  C  the  cloud  will 
seem  to  move  away  from  the  center  of  the  mirror.  But  he  may,  if  he 
choose,  so  move  his  eye  that  the  image  of  the  knob  shall  continually 
cover  the  selected  point  of  cloud,  and  if  he  does  this,  then  both  cloud 
and  knob  will  appear  to  move  together  away  from  the  center  of  the 
mirror.  This  latter  is  the  method  of  observation  that  is  always  to  be 
recommended,  and  if  one  could  keep  the  cloud  and  knob  together 
until  tteir  reflections  simultaneously  reach  the  edge  of  the  graduated 
rim,  he  could  then  read  on   the  rim  an  angle  that  represents  the 


166  CHICAGO    METEOROLOGICAL    CONGRESS. 

azimuthal  direction  of  their  motion  relative  to  the  zero  of  that  circle. 
The  position  of  this  zero  with  reference  to  the  lubber  line,  FA,  of  the 
vessel  is  given  by  taking  from  the  same  circle  the  reading  correspond- 
ing to  the  forward  end  of  the  line,  F;  the  relation  of  F  to  the  magnetic 
meridian  is  given  by  taking  from  the  compass  card,  as  seen  through 
the  unsilvered  glass,  the  angle  corresponding  to  the  same  forward  end 
of  the  line,  AF;  the  relation  of  the  magnetic  to  the  true  meridian  is 
known  from  the  tables  of  deviations  and  variations.  These  four 
angular  readings,  when  added  together,  give  the  true  azimuth  of  the 
apparent  motion  of  the  cloud. 

Inasmuch  as  we  do  not  often  care  to  wait  as  long  as  is  necessary 
for  the  image  of  the  cloud  and  knob  to  move  from  the  center  to  the 
edge  of  the  mirror,  and  especially  since  it  continually  happens  that 
the  cloud  disappears  or  becomes  unrecognizable  in  the  midst  of  an 
observation,  it  is  necessary  to  provide  for  that  class  of  observations 
which  really  occurs  most  frequently,  namely,  where  the  cloud  is  fol- 
lowed only  out  to  the  first  small  circle  whose  radius  in  the  present 
apparatus  is  exactly  one  inch ;  I  have,  therefore,  provided  a  black 
copper  wire  or  silk  thread  that  stretches  entirely  across  the  circular 
mirror  and  is  attached  to  a  rather  heavy  wire  forming  a  circle  adjacent 
to  the  inner  edge  of  the  rim.  As  this  circle  with  its  wire  must  be 
easily  turned  in  azimuth,  there  are  provided  two  small  handles,  h  and 
h ;  by  taking  hold  of  these  the  observer  easily  brings  the  thread  into 
such  a  position  that  both  cloud  and  knob  traverse  it  together  as  they 
move  across  the  mirror,  and  no  matter  how  short  their  path  may  be, 
the  azimuth  of  their  motion  is  easily  read  at  the  end  of  the  thread. 
We  thus  provide  all  that  is  necessary  in  order  to  obtain  either  the 
true  or  the  magnetic  bearing  of  the  movement  of  the  cloud.  It  is 
easy  to  see  how  one  may  utilize  the  same  thread  to  determine  the  azi- 
muthal trend  of  the  trail  of  smoke  which  a  steamer  leaves  in  its  wake, 
or  the  trend  of  the  streamers  and  pennants  seen  reflected  in  the 
mirror,  and,  as  all  these  depend  upon  the  combined  motion  of  the 
wind  and  vessel,  they  have  been  subjects  of  regular  observation  by 
myself  on  the  U.  S.  S.  Pensacola.  Moreover,  when  one  wishes  to  ob- 
serve the  trend  of  the  troughs  and  ridges  of  waves,  or  of  the  foam 
that  flecks  the  water  with  white  streaks  during  high  winds,  he  has 
here  an  apparatus  more  convenient  and  accurate  than  the  estimates 
of  any  but  the  most  skilful  navigators,  as  I  can  testify  from  consid- 
erable personal  experience.  Not  only  the  motions  of  the  clouds,  but 
general  trend,  or  the  vanishing  points  of  special  formations  in  the 
cirrus  clouds,  the  boundaries  of  cloud  rolls,  the  location  of  the 
zodiacal  light,  and  the  dimensions  of  halos  and  rainbows,  are  easily 
determined. 

By  determining  the  apparent  angular  altitude  and  the  apparent 
velocity  per  second  of  the  cloud  under  observation,  when  a  vessel  is 


THE    BAROMETER    AT    SEA.  167 

going  at  different  speeds  and  in  different  directions,  we  may  compute 
the  actual  velocity  and  height  of  the  cloud.  But  I  will  not  here  enter 
upon  a  complete  account  of  the  many  problems  that  can  be  solved 
with  the  help  of  this  simple  apparatus ;  they  are  mostly  questions 
that  interest  the  meteorologist  rather  than  the  navigator.  The  latter 
needs  the  nephoscope  mostly  in  order  to  determine  the  true  direction 
of  motion  of  the  clouds,  and  for  this  purpose,  if  his  vessel  is  a 
steamer,  he  first  observes  the  apparent  direction  of  motion  as  seen  in 
the  nephoscope  when  going  ahead  at  his  ordinary  speed;  he  then 
slows  up  a  little  for  five  minutes  and  takes  another  observation  and, 
if  he  can,  slows  up  for  another  five  minutes  and  after  getting  a  third 
observation  resumes  his  full  speed  and  takes  a  final  observation.  The 
difference  between  the  results  obtained  at  high  speed  and  low  speed 
enables  him  to  easily  find  what  the  true  direction  of  the  cloud  motion 
is  or  as  it  would 'be  observed  if  the  vessel  were  stationary.  If  the 
navigator  is  on  a  sailing  vessel  it  is  easier  for  him  to  observe  on  two 
different  tacks  and  the  comparisons  of  the  results  thus  obtained  will 
give  him  the  true  motion  of  the  clouds.  When  the  wind  has  a 
strength  above  force  6  on  the  Beaufort  scale,  the  movements  of  the 
lower  clouds  are  apt  to  be  so  much  more  rapid  than  those  of  any 
sailing  vessel  that  the  cloud  movement  is  given  with  sufficient  ap- 
proximation by  single  observations  without  the  necessity  of  combining 
those  made  on  different  tacks.  Convenient  numerical  tables  will  be 
published  in  a  "  Manual  of  the  Nephoscope." 


4.— THE  BAROMETER  AT  SEA. 
T.  S.  O'Leary. 

Ever  since  Torricelli,  that  brilliant  pupil  of  Gallileo,  made  his 
famous  experiments  in  1643,  the  barometer  has  been  both  a  familiar 
and  valuable  instrument  to  all  civilized  nations.  It  is  now  absolutely 
necessary  in  conducting  all  scientific  experiments  where  the  pressure 
of  the  atmosphere  is  a  factor.  But  so  much  has  been  written  on  its 
construction,  care,  uses,  and  reliability,  it  would  be  a  waste  of  time  to 
attempt  to  cover  ground  that  has  already  been  so  carefully  gone  over. 
As  the  subject  is  a  large  one  it  is  much  beyond  the  scope  of  this  paper 
to  treat  it,  though  briefly,  in  all  its  phases  in  the  time  allowed.  I 
shall  confine  myself,  therefore,  to  a  few  general  remarks. 

Although  the  U.  S.  Hydrographic  Office  has  been  collecting  ocean 
data  ever  since  the  time  of  INIaury,  it  has  been  within  the  past  few 
years  that  special  efforts  have  been  made  to  systematize  the  collection 
of  these  data  and  use  of  the  same.  A  great  step  forward  was  made 
when  the  meteorological  log  journal,  which  required  observations  to 
be  made  at  twelve  different  times  during  every  twenty-four  hours, 


168  CHICAGO    METEOROLOGICAL   CONGRESS. 

was  superseded  by  the  meteorological  log  book,  which  requires  but 
one  regular  observation  to  be  made  daily.  The  hour  fixed  is  noon, 
Greenwich  mean  time,  so  that  no  matter  in  what  part  of  the  ocean 
the  observations  are  being  made  the  observers  are  acting  simultane- 
ously. This  simplified  log  was  found  to  be  much  more  desirable  than 
the  journal,  as  observers  were  induced  to  continue  the  w^ork,  who, 
after  filling  one  journal,  were  apt  to  decline  keeping  another  on  ac- 
count of  the  labor  involved.  The  result  has  been  that  the  number  of 
observers  has  increased  nearly  eight  fold,  so  that  the  oceans  are  now- 
dotted  with  many  interested  workers. 

Another  valuable  feature  is  the  indenture  of  the  leaves  of  the  new 
log  book,  which  enables  the  observers  to  remove  the  pages  as  fast  as 
they  are  filled  up  and  forward  them  to  the  Hydrographic  Office,  there 
to  be  utilized  in  current  work.  The  master  of  a  vessel,  or  the  observer, 
wants  to  see  the  results  of  his  observations  w^hile  the  facts  are  still 
fresh  in  his  memory  and  while  he  is  yet  interested  in  what  has  re- 
cently taken  place.  The  Pilot  Chart  of  the  North  Atlantic  attempts 
to  satisfy  this  want  by  placing  before  the  mariner  in  a  graphic  form 
such  matters  as  are  deemed  of  interest  or  importance  to  him.  For 
his  time  and  trouble  the  observer  wants  a  ready  return  if  possible. 
The  accumulation  of  several  years'  data  in  the  home  meteorological 
offices,  there  to  he  compiled  at  leisure,  then  to  appear  in  a  volume 
too  bulky  for  reading  and  too  scientific  for  the  ordinary  navigator, 
with  too  much  attention  paid  to  minor  details,  is  a  danger  which 
should  be  carefully  guarded  against. 

The  past  has  shown  that  the  above  cause  has  driven  from  the  field 
many  good  observers  who  were  once  interested,  and  kept  out  of  the 
field  many  more  whose  co-operation  would  have  been  of  the  greatest 
value.  The  loss  of  their  services  is  a  direct  loss  to  the  science  of 
marine  meteorology,  but,  let  us  hope,  it  is  not  too  late  to  again  stim- 
ulate them  to  further  efforts. 

It  goes  without  saying  that  mercurial  barometers  are  the  best  and 
most  reliable,  but,  unfortunately,  a  good  mercurial  instrument  is  an 
expensive  one.  For  this  reason  many  sea-going  vessels  are  supplied 
with  aneroids  only.  Some  are  supplied  with  both,  but  generally  the 
mercurial,  the  reliable  one,  is  placed  in  the  captain's  cabin,  where  he 
alone  has  access  to  it.  On  other  vessels  it  is  often  placed  too  high, 
where  the  light  is  not  good,  or  more  with  regard  to  its  safety  than  its 
accessibility,  so  that  on  a  dark  night,  during  heavy  weather,  the 
observer  experiences  no  little  difficulty  in  getting  even  an  approxi- 
mate reading.  Generally  speaking,  the  placing  of  many  barometers, 
especially  in  merchant  ships,  is  in  the  interest  of  the  vessel  and  its 
owners  and  not  in  the  interest  of  science.  We  must  accept  the  situa- 
tion as  we  find  it,  and  deduce  from  the  data  furnished  the  best  results 
we  can. 


THE    BAROMETER    AT    SEA.  169 

First  of , all,  the  most  important  thing  in  considering  a  set  of  barom- 
eter readings  is  to  determine  the  reliability  of  the  instrument  and 
observer.  To  do  this  frequent  comparisons  with  a  standard  barometer 
are  necessary  of  readings  recorded  hy  the  observer  himself. 

A  simple  plan  for  obtaining  these  comparisons  has  been  in  use  by 
the  U.  S.  hydrographic  offices  for  the  past  three  years,  and  the  results 
obtained  have  been  most  satisfactory.  The  credit  of  the  plan  is  due 
to  the  force  employed  in  the  Meteorological  Division  of  the  Hydro- 
graphic  Office  at  Washington,  which  plan  was  arrived  at  after  the 
mistakes  and  difficulties  of  former  methods  in  use  had  been  clearly 
demonstrated.  I  can  not  do  better  than  give  an  account  of  the  plan 
now  in  use.  Although  simple  in  the  extreme,  it  answers  all  practical 
purposes. 

On  the  arrival  of  a  vessel  in  port  the  meteorological  reports  are 
forwarded  immediately  to  the  nearest  branch  hj^drographic  office. 
Accompanying  the  acknowledgement  of  the  receipt  of  these  reports 
are  two  or  more  franked  postal  barometer  cards,  on  the  back  of  which 
are  brief  instructions  showing  how  the  columns  should  be  filled. 
When  in  ports  of  the  United  States  or  Canada,  observers  are  requested 
to  record  the  readings  of  the  barometer  used  for  observations  at  sea 
at  8  a.  m.  or  8  p.  m.,  seventy-fifth  meridian  time,  as  at  those  hours 
the  U.  S.  Weather  Bureau  observers  record  their  observations.  If 
the  vessels  are  in  those  ports  where  branch  hydrographic  offices  are 
located,  readings  at  other  times  will  answer,  as  a  record  is  kept  of  the 
hourly  readings  of  the  standard  in  each  office.  When  the  cards  have 
been  properly  filled  out  they  are  mailed  by  the  observer  to  the  branch 
hydrographic  office,  where  each  reading  is  compared  with  that  of  the 
standard  instrument  for  the  corresponding  time.  A  cop}'^  of  these 
comparisons  is  immediately  furnished  the  observer.  The  original 
cards  are  forwarded  to  the  Hydrographic  Office  at  Washington,  where 
the  comparisons  are  examined  and  copied,  after  which  they  are  re- 
turned to  the  branch  offices  whence  they  came,  there  to  be  filed  away, 
so  that  any  master  or  observer  can  readily  find  out  how  his  barometer 
has  been  acting  from  month  to  month  or  from  year  to  year.  In 
making  these  comparisons  it  has  been  found  best  to  take  the  absolute 
difference  between  the  reading  of  an  aneroid  and  the  corrected  read- 
ing of  the  standard  as  the  total  correction  to  be  applied  to  all  the 
readings  of  the  aneroid  for  that  pressure.  With  mercurial  barome- 
ters the  reading  is  first  corrected  for  temperature;  the  difference, 
then,  between  that  result  and  the  corrected  reading  of  the  standard 
is  the  correction  to  be  applied  to  the  reading  of  the  mercurial.  It  is 
evident  that  these  total  corrections  are  but  the  algebraic  sum  of  the 
instrumental  error,  correction  for  altitude,  and  personal  error  of  the 
observer.  This  last  error  is  of  no  little  consequence,  for  if  the  ob- 
server is  not  faithful  in  recording  the  observations  at  the  proper  time, 


170  CHICAGO    METEOROLOGICAL    CONGRESS. 

his  work  is  no  more  reliable  than  that  of  a  faithful  observer  with  an 
inferior  instrument. 

It  might  be  contended  that  the  corrections  obtained  from  compar- 
isons made  in  port  when  the  vessel  is  light  would  not  answer  when 
she  was  at  sea  deep  laden.  Supposing  this  difference  in  heights  of  the 
barometer  to  be  15  or  20  feet  the  difference  of  correction  would  be 
only  one  or  two  hundredths,  an  unnecessary  refinement  when  it  is 
remembered  that  in  the  height  of  the  storm,  or  when  the  mercury  is 
"pumping"  considerably,  an  approximate  reading  is  all  that  can  be 
obtained. 

Another  method  of  obtaining  comparisons,  which  has  proved  quite 
satisfactory,  is  by  making  use  of  the  isobars  on  the  U.  S.  Weather 
Maps  and  the  readings  at  the  stations  along  the  coast.  As  the  morn- 
ing readings  are  taken  at  8  o'clock,  seventy-fifth  meridian  time  (or  1 
p.  m.,  Greenwich  mean  time),  there  is  only  an  hour's  difference 
between  the  shore  readings  and  the  readings  at  sea.  Under  normal 
conditions  this  is  not  of  much  consequence,  especially  when  the  pres- 
sure changes  only  a  few  hundredths  in  as  many  hours.  Use  is  made, 
also,  of  the  2  p.  m.  readings  of  the  British  Daily  Weather  Report.  It 
will  be  seen  that  "  checks  "  obtained  from  the  readings  of  a  vessel's 
barometer  while  in  the  vicinity  of  Key  West,  Jupiter,  Hatteras,  Block 
Island,  or  Nantucket  on  this  side,  and  again  near  the  outer  stations, 
such  as  Moville,  Valentia,  Bishop's  Rock,  or  Dungeness  on  the  other, 
would  determine  pretty  well  whether  or  not  the  readings  for  the  voy- 
age should  be  rejected. 

These  comparisons  are  often  the  only  ones  obtainable,  as  the  many 
duties  of  the  officers  while  in  port  leaves  them  little  or  no  time  for 
filling  out  blanks.  Hence,  the  importance  of  these  shore  readings 
when  vessels  are  adjacent  to  the  stations.  It  might  be  mentioned  in 
this  connection  that  the  readings  recorded  on  the  vessels  at  the  time 
are  obtained  under  the  same  conditions,  most  likely,  as  those  recorded 
for  the  previous  or  subsequent  part  of  the  voyage,  which  fact  lends 
value  to  the  comparisons. 

This  second  method  of  obtaining  comparisons  is  confined  at  present 
to  vessels  approaching  or  leaving  the  east  coast  of  the  United  States 
or  the  coasts  of  Europe.  It  is  to  be  hoped,  however,  that  in  the  near 
future  reliable  readings  from  standard  instruments  for  noon,  Green- 
wich time,  will  be  promptly  furnished  from  the  Azores,  Canaries, 
Cape  Verde,  and  West  Indies,  so  that  corrections  for  vessels'  barom- 
eters can  be  obtained  in  much  the  same  manner  that  a  navigator 
determines  his  chronometer  error  when  in  the  vicinity  of  a  place,  the 
latitude  and  longitude  of  which  have  been  accurately  determined. 
Without  a  good  idea  of  the  approximate  correction  to  be  applied  to 
the  readings  furnished,  the  investigator  will  find  it  quite  difficult  to 
harmonize  ocean  barometric  data. 


THE    BAROMETER    AT    SEA.  171 

It  is  to  be  regretted  that  the  morning  observations  for  the  U.  S 
Weather  Service  are  not  made  an  hour  earlier,  and  the  2  p.  m.  obser- 
vations of  the  British  Weather  Service  two  hours  earlier.  If  such 
were  the  case,  the  observers,  both  on  land  and  at  sea,  would  be  work- 
ing in  conjunction  with  each  other,  and  the  simultaneous  observa- 
tions would  extend  over  Europe,  the  United  States,  and  all  the  oceans. 
In  the  northern  hemisphere  particularly  could  the  meteorological 
conditions  be  studied  to  better  advantage,  with  observations  taken  at 
the  same  time  over  an  area  extending  from  Russia  on  the  east  to  the 
east  coast  of  Asia  on  the  west,  or  over  two  hundred  and  fifty  degrees 
of  longitude.  The  importance  of  the  change  suggested  and  the  ben- 
efit resulting  therefrom  are  worthy  of  serious  consideration. 

The  records  of  the  Hydrographic  Office  for  the  past  three  years 
show  that  on  5,425  voyages  or  parts  of  voyages  made  by  1,600  vessels 
the  readings  of  the  mercurial  barometers  were  deemed  reliable  in 
4,321  cases,  while  in  the  remaining  1,104  cases  they  were  discarded  or 
considered  doubtful.  With  the  aneroids,  out  of  a  total  of  8,898  voy- 
ages or  parts  of  voyages,  in  4,160  cases  the  readings  were  considered  re- 
liable, and  in  4,738  cases  unreliable.  In  other  words,  80  per  cent  of 
the  mercurial  readings  could  be  fairly  depended  upon  and  only  46 
per  cent  of  the  aneroids.  These  represent  about  250,000  barometer 
readings  for  the  North  Atlantic,  of  which  about  130,000  were  plotted 
and  120,000  discarded.  The  large  per  cent  of  unreliable  readings  can 
be  attributed  to  many  causes,  some  of  which  are  inferior  instruments, 
carelessness  in  reading,  wrong  time  for  observing,  and  wrong  position 
given  for  time  of  observation.  Many  of  these  mistakes  have  been 
corrected  as  the  observers  have  grown  more  familiar  with  the  work. 
This  is  evidenced  by  the  decided  improvement  to  be  noticed  in  the 
consistency  of  the  readings  plotted  in  the  successive  volumes  of  the 
daily  synoptic  maps  of  the  North  Atlantic.  It  is  fair  to  presume 
that  in  a  short  time  80  or  85  per  cent  of  all  the  barometric  readings 
received  will  be  plotted  instead  of  63  per  cent,  as  previously  shown. 

The  large  difference  in  per  cent  between  the  reliable  mercurial  ba- 
rometers and  reliable  aneroids  will  not  escape  notice,  and  while  the 
superiority  of  the  former  instruments  is  undoubtedly  established 
I  would  hesitate  long  before  casting  aside  the  readings  of  all  aneroids 
simply  because  they  were  aneroids.  In  many  instances,  especially  in 
those  parts  of  the  ocean  the  least  frequented,  readings  from  aneroids 
are  the  only  ones  obtainable.  With  a  fair  correction  these  readings 
assist  to  establish  the  origin  of  a  "  low,"  perhaps,  or  prolong  a  storm 
track  beyond  the  well-defined  paths  of  commerce.  Although  mer- 
curial readings  are  to  be  preferred  the  prejudice  against  aneroids 
should  not  be  too  strong.  While  some  are  bad  all  the  time,  not  all 
are  bad  all  the  time.  The  lowest  reading  plotted  on  any  of  the  daily 
synoptic  maps  is  that  of  an  aneroid,  which  was  considered  tolerably 


172  CHICAGO    METEOROLOGICAL    CONGRESS. 

reliable.  At  10  a.  m.,  Greenwich  mean  time,  February  1,  1892,  the 
British  steamship  Bellini,  in  N.  59°  38',  W.  7°  02',  had  a  barometer 
(aneroid)  reading  of  27.47  inches.  Appljnng  the  correction,  -j-0-15, 
for  this  instrument,  the  corrected  reading  would  be  27.62  inches.  As 
the  reading  recorded  by  the  observer  of  the  British  Weather  Service 
at  Sumburgh  Head  at  6  p.  m.  of  that  day  was  28.02  inches,  with  steep 
gradients  to  the  westward,  and  as  the  storm  center  passed  to  the  north- 
west of  the  Shetland  Islands,  it  is  not  unlikely  that  the  corrected 
reading  of  the  BelUni\s  barometer,  180  miles  west  of  Sumburgh,  and 
near  the  storm  center,  was  not  far  from  a  correct  pressure.  The  cor- 
rection applied  in  this  instance,  -j-0.15,  was  obtained  from  comparisons 
on  this,  the  preceding,  and  the  subsequent  voyage. 

The  next  lowest  reading  plotted  is  that  of  the  Dutch  steamship 
Wei'kendam.  in  the  cyclone  of  December  22-23,  1892.  At  2  a.  m., 
Greenwich  mean  time,  December  23,  in  N.  49°  41',  W.  30°  41',  the 
corrected  reading  of  this  instrument  (mercurial)  was  704  mm.,  or 
27.72  inches. 

The  highest  reading  so  far  plotted  is  790  mm.,  or  31.10  inches,  the 
corrected  reading  of  the  German  steamship  Fulda\s  mercurial  barom- 
eter, at  noon,  Greenwich  mean  time,  January  14,  1891,  in  N.  49°  57', 
W.  14°  50'.  These  readings  would  indicate  that  at  sea  the  greatest 
range  of  the  barometric  column  occurs  in  the  high  latitudes  during 
the  winter  months,  the  same  as  on  land,  and  is  about  84  mm.,  or  3.5 
inches. 

The  importance  of  frequent  comparisons  can  not  be  overestimated. 
To  illustrate,  the  mecurial  barometer  of  a  well-known  trans-Atlantic 
liner  after  being  quite  regular  for  two  years  suddenly  changed  so 
that  a  correction  of  -}-0.78  of  aa  inch  was  necessary.  The  observer 
being  notified  of  the  fact  began  using  an  aneroid.  The  latter  instru- 
ment was  found  to  be  0.50  of  an  inch  too  high.  Here,  then,  were  two 
barometers  on  the  same  vessel  with  a  difference  of  1.38  inch  in  their 
readings.  This  is,  perhaps,  an  exceptional  c*ase,  but  it  shows  that 
each  and  every  barometer  should  be  carefully  "  checked  "  before  the 
readings  are  plotted  as  final.  Out  of  the  1,600  vessels  previously 
mentioned  the  author  has  taken  70  that  had  good  barometer  records. 
The  records  show  that  of  these  barometers  60  were  mercurial  and 
10  aneroid,  and  that  the  average  variation  of  the  70  barometers  over  a 
period  of  twenty-five  months  was  only  0.04  of  an  inch.  Only  those 
records  were  taken  where  the  variation  in  the  correction  applied  was 
less  than  0.10  of  an  inch,  and  where  the  barometer  had  been  in  use 
more  than  a  year.  The  superiority  of  the  mercurial  barometers  is 
here  again  shown  by  a  ratio  of  6  to  1.  Of  the  60  mercurial  barom- 
eters it  was  necessary  to  apply  a  plus  correction  with  50  and  a  minus 
correction  with  the  remaining  10,  which  fact  might  indicate  that 
even  with  the  good  observers  the  tendency  is  in  reading  mercurial 
barometers  to  move  the  vernier  too  far  down  and  thus  read  too  low. 


THE    BAROMETER    AT   SEA.  173 

An  intelligent  interpretation  of  the  prevailing  conditions  as  indi- 
cated by  the  barometer,  direction  and  force  of  wind,  state  of  sea,  and 
atmosphere,  with  a  view  to  not  only  the  present,  but  the  future  action 
of  his  vessel,  should  be  the  object  of  every  mariner.  At  the  approach 
of  a  cyclone,  or  even  when  the  storm  is  on,  the  action  of  the  barom- 
eter together  with  the  shifts  of  wind  will  determine  the  all  important 
point  of  which  tack  to  lay  the  vessel  on.  This  done,  and  the  storm 
passed,  the  next  thing  is  to  take  advantage  of  the  future  shifts  by  so 
laying  the  course,  when  first  able  to  proceed,  that  the  different  shifts 
will  be  provided  for  beforehand  and  the  vesssl  allowed  to  continue 
on  her  way  without  the  probability  of  being  headed  off.  Good  judg- 
ment in  this  direction,  based  upon  the  knowledge  we  already  have  of 
the  general  laws  of  atmospheric  movements,  will  often  serve  to  shorten 
the  passage  and  bring  the  vessel  into  port  without  much  working.  It 
is  not  only  in  bad  weather,  but  in  good  weather  also  that  the  master 
should  be  on  the  alert.  The  approach  of  a  "  high,"  with  successive 
shifts  of  wind  due  to  that  circulation,  should  be  as  well  understood 
and  maneuvered  for  as  the  approach  and  shifts  of  a  "  low,"  and  for 
the  same  reasons  as  given  above.  This  important  subject  is  worthy 
of  the  fullest  investigation  and  should  be  thoroughly  mastered  by 
every  navigator. 

In  conclusion,  I  would  beg  to  submit  for  your  consideration  the 
following  suggestions : 

That  the  members  of  this  Congress  impress  upon  their  respective 
governments  the  desirability  and  importance  of  a  least  one  set  of 
simultaneous  observations  taken  daily ;  that  the  hour  be  noon,  Green- 
wich time,  for  reasons  previously  mentioned ;  that  all  barometer  read- 
ings be  "checked  "  by  frequent  comparisons  before  being  used;  that 
a  uniform  and  simple  system  of  recording  observations  by  mariners 
be  adopted ;  that  the  recording  of  observations  be  encouraged  among 
shipmasters  and  officers,  and  also  the  study  of  ocean  meteorology  by 
putting  before  them  from  time  to  time,  and  in  as  graphic  a  manner 
as  possible,  the  explanation  of  the  general  laws  of  atmospheric  move- 
ments and  such  other  matters  as  would  be  beneficial  to  them ;  and 
finally,  that  all  the  data  collected  be  used  in  an  exhaustive  manner 
to  the  end  that  from  a  thorough  investigation  of  the  results  obtained 
our  knowledge  of  the  subjecf  of  ocean  meteorology  may  be  consider- 
ably increased. 


174  CHICAGO    METEOROLOGICAL    CONGRESS. 


6.— THE  SECULAR  CHANGE  IN  THE  DIRECTION  OF  THE  MAG- 
NETIC NEEDLE;    ITS  CAUSE  AND  PERIOD. 

G.    W.    LiTTLEHALES. 

A  freely  suspended  magnetic  needle  is  observed  to  be  in  a  state  of 
continuous  tremulous  motion  of  an  involved  character  which  may  be 
resolved  into  irregular  and  periodic.  The  irregular  motions  comprise 
those  sudden  and  rapid  fluctuations  in  the  direction  of  the  needle 
which  can  not  be  predicted.  The  periodic  motions  are  the  solar  vari- 
ations which  include  the  solar-diurnal  variation  depending  upon  the 
hour  of  the  day,  the  annual  variation  depending  upon  the  day  of  the 
vear.  and  the  solar-synodic  variation  depending  upon  the  synodic 
revolution  of  the  sun,  the  lunar  variations  depending  upon  the 
moon's  hour-angle  and  her  other  elements  of  position,  and  partaking 
of  the  character  of  the  tides,  and  the  decennial  variations  which  may 
depend  upon  the  frequency  and  magnitude  of  the  solar  spots.  Both 
the  irregular  and  periodic  motions  referred  to  are  of  such  small  am- 
plitude in  all  except  the  polar  regions  of  the  earth  that  they  do  not 
effect  any  of  the  practical  uses  of  the  magnetic  needle  on  the  sea, 
but  besides  these  there  is  another  motion,  having  an  amplitude  reach- 
ing thirt}'"  or  forty  degrees  in  some  parts  of  the  world,  which  is  also 
supposed  to  be  of  periodic  character,  and  Avhich,  although  not  per- 
haps so  intimately  connected  with  the  meteorologic  problems  of  the 
day  as  the  variations  of  smaller  amplitude  and  period,  is  doubtless 
of  radical  importance  in  meteorologic  science. 

At  a  particular  instant  of  time  the  lines  of  magnetic  force  at  any 
place,  to  which  a  freely  suspended  magnetic  needle  will  set  itself  tan- 
gent, will  have  a  certain  direction  and  strength.  The  angle  between 
the  plane  of  the  astronomical  meridian  and  the  vertical  plane  passing 
through  the  needle,  or  the  line  of  force,  is  the  magnetic  declination, 
or  the  variation  of  the  compass ;  the  angle  between  the  horizon  and 
the  direction  of  the  needle,  measured  in  the  vertical  plane  passing 
through  it,  is  the  dip,  or  inclination ;  and  the  force  with  which  the 
needle  is  held  in  the  direction  of  the  lines  of  force  is  called  the  mag- 
netic intensity.  The  declination  and  inclination,  or  the  directional 
elements,  which  alone  are  concerned  in  a  discussion  of  the  motion  of 
the  magnetic  needle,  have  always  been  treated  separately  in  investi- 
gating the  secular  change  of  the  magnetic  needle.  From  1634,  when 
the  fact  of  the  secular  variation  of  the  declination  was  established, 
and  from  1676,  when  the  inclination  or  dip  was  discovered,  reliable 
observations  of  these  respective  elements  are  recorded  for  the  great 
populous  centers  of  Europe,  and  soon  observations  of  the  declination 
or  variation  of  the  compass,  a  knowledge  of  which  is  necessary  to 
mariners  in  the  navigation  of  their  ships,  had  been  made  by  navi- 


SECULAR    CHANGE   OF    MAGNETIC    NEEDLE.  175 

gators  in  most  of  the  known  parts  of  the  world.  Although  the  older 
observations,  having  been  made  without  the  means  of  precise  meas- 
urement, are  subject  to  a  probable  error  of  as  much  as  1°,  they  can 
be  accepted  as  serviceable  in  the  discussion  of  long  series  and  serve  to 
reveal  satisfactorily  the  secular  change  of  the  declination.  Through 
the  results  of  the  observations  of  the  navigators  of  successive  periods, 
series  of  observations  of  the  declination  extending  over  two  or  three 
centuries  are  available  for  most  of  the  important  maritime  stations 
of  the  world.  On  plotting  the  observations  at  a  given  station  with 
reference  to  rectangular  co-ordinates,  using  values  of  the  declination 
as  ordinates  and  intervals  of  time  as  abscissa?,  sinuous  curves  are 
developed  which  suggest  the  periodic  character  of  the  secular  varia- 
tion, and  it  is  now  customary  to  adapt  to  the  series  of  observations 
for  their  discussion  a  periodic  function  of  the  form 

.    .    D     •      360     ,    „          360 
V=:A-{-B.  sin. (  4-  B„  cos. t, 

in  which  V  represents  the  variation,  m  the  period  of  the  cycle,  t  the 
time  in  years  and  fractions  of  a  year  reckoned  from  some  assumed 
epoch,  and  A,  B^,  and  B^  constants  to  be  determined  from  the  obser- 
vations. 

In  this  manner  the  rate  of  movement  of  the  compass  needle  is  found 
for  any  epoch  within  the  range  of  observation,  the  times  when  the 
needle  is  stationary  are  computed,  and  values  of  the  declination  are 
predicted  for  current  use  for  ten  or  fifteen  years  beyond  the  limits  of 
observation  within  an  assigned  measure  of  precision.  An  examina- 
tion of  the  curves  resulting  from  plotting  the  observed  and  computed 
values  of  the  declination  at  a  few  stations,  where  the  series  extend  over 
the  greatest  duration  and  are  the  most  complete,  will  show  upon  what 
evidence  rests  the  widespread  belief  that  the  secular  variation  of  the 
magnetic  declination  is  a  periodic  phenomenon. 

There  are  also  available  for  discussion  series  of  observations  of  the 
dip  or  magnetic  inclination  ranging  from  one  hundred  to  three  hun- 
dred years  in  duration,  but  the  stations  are  not  so  numerous  nor  the 
observations  so  complete  as  in  the  case  of  the  declination,  except  in 
the  long-settled  regions  of  European  civilization.  This  is  accounted 
for  by  the  fact  that  the  dip  was  rarely  observed  by  navigators,  except 
when  employed  in  expeditions  of  scientific  research,  while  the  decli- 
nation was  found  as  a  necessary  performance  in  the  navigation  of 
their  ships.  The  investigation  of  the  longer  series  has  led  to  the  be- 
lief that  the  secular  variation  of  the  inclination  is  also  a  periodic 
phenomenon ;  but  the  data  which  have  been  observed  up  to  the  pres- 
ent are  manifestly  insufficient  to  warrant  a  conclusion  that  after  a 
certain  period  has  elapsed  the  declination  at  any  given  station  will  be 
the  same  as  it  is  now  and  will  then  repeat  its  changes  and  again 
assume  the  same  value  after  the  lapse  of  the  same  interval  of  time,  or 


176  CHICAGO    METEOROLOGICAL   CONGRESS. 

that  the  inclination  at  that  place  will  be  found  to  pass  through  a 
cycle  of  changes  and  return  to  the  same  value  at  regular  intervals  of 
time.  While  the  separate  investigation  of  series  of  observations  of 
declination  and  inclination  is  of  great  practical  usefulness  in  gaining 
a  knowledge  of  the  rate  of  secular  change  of  these  elements  and  pre- 
dicting values  beyond  the  range  of  the  observations,  in  seeking  to  dis- 
cover the  causes  of  the  secular  change  in  the  direction  of  the  magnetic 
needle  and  to  establish  or  disprove  its  periodic  character  the  declina- 
tion and  inclination  should  be  viewed  as  component  effects  of  the 
forces  that  are  acting.  Such  a  view  brings  us  to  the  investigation  of 
the  successive  directions  in  space  assumed  at  successive  epochs  by  a 
freely  suspended  magnetic  needle  or  the  consideration  of  the  ob- 
served values  of  the  declination  and  inclination  conjointly,  instead 
of  the  separate  consideration  of  values  of  the  direction  of  the  com- 
pass needle  and  of  the  dipping  needle.  As  a  freely  suspended  mag- 
netic needle  assumes  its  successive  directions  for  different  times,  it 
describes  a  conical  surface  whose  vertex  is  the  center  of  gravity  of 
the  needle. 

If  a  sphere  of  any  convenient  radius  be  described,  with  its  center 
coinciding  with  the  center  of  gravity  of  the  needle,  and  the  conical 
surface  be  extended  through  the  surface  of  the  sphere,  the  line  of  in- 
tersection will  be  a  serpentine  curve  whose  geometrical  nature  should 
be  full}^  investigated,  since  it  represents  the  actual  secular  motion  of 
the  needle.  Preliminary  analytical  and  graphical  attempts  have  been 
made  by  Quetelet,  of  Brussels,  Schaper,  of  Lubeck,  and  the  mathe- 
maticians of  the  Coast  and  Geodetic  Survey.  The  scantiness  of  data 
has  prevented  any  safe  deductions  as  to  the  future  course  of  the  needle. 

At  the  present  time  we  know,  with  moderate  accuracy,  the  values 
of  the  three  magnetic  elements  for  the  inhabited  portions  of  the  world, 
and  also,  with  a  lesser  accuracy,  the  rates  of  secular  change  in  the 
elements,  but  we  have  rjo  knowledge  as  to  whether  the  needle,  when 
it  points  in  a  certain  direction  at  a  given  place,  will  ever  return  to 
the  same  position  again,  or  whether  it  will  at  the  end  of  a  certain 
period  assume  the  same  direction  again,  and  again  sweep  over  the 
same  path  in  the  same  period.  Nor  do  we  know  that  the  secular- 
variation  period,  if  there  shall  hereafter  be  found  to  be  one,  will  be 
the  same  in  all  parts  of  the  world. 

To  promote  the  study  of  the  secular  change  it  is  proposed  that  this 
Congress  shall  take  steps  to  secure  the  co-operation  of  observers  at 
the  following-named  places  to  make  yearly  observations  of  the  dip 
and  declination  at  selected  stations  and  to  arrange  and  transmit 
them  to  the  U.  S.  Hydrographic  Office  at  Washington  where  their 
discussion  will  be  undertaken  : 


BAROMETRIC    PRES^RE    AND    OCEAN    CURRENTS.  177 


Christianshaab T. .  .Greenland. 

Saint  Johns Newfoundland. 

Acapulco Mexico. 

Mazatlan do. 

Mexico do. 

VeraCruz do. 

San  Juan  del  Sur Nicaragua. 

Callao Peru. 

Conception Chile. 

Valparaiso do. 

Belize British  Honduras. 

Cartagena U.  S.  of  Colombia. 

Colon do. 

Panama do. 

La  Guayra Venezuela. 

Kingston Jamaica. 

Port  Castries West  Indies. 

Saint  Thomas do. 

Bahia Brazil 

Para do. 

Pernambuco do. 

Rio  de  Janeiro  do. 

Montevideo Uruguay. 

Buenos  Ayres Argentine  Republic. 

Sandy    Point  (Punta 

Arenas)    Patagonia. 

The  Azores 

The  Canaries 

Cape  Verde 

Bermuda 


Cape  of  Good  Hope. ..Africa. 

Congo  River do. 

Delagoa  Bay do. 

Libreville do. 

Loanda do. 

Port  Natal do. 

Quilimane  River do. 

Zanzibar do. 

Port  Louis Mauritius. 

Hellville Madagascar. 

Aden Arabia. 

Singapore Malay  Peninsula. 

Saigon Siam. 

Pekin China. 

Hakodate Japan. 

Nagasaki do. 

Vladivostok Siberia. 

Petropaulovsk Kamchatka. 

Sitka Alaska. 

Unalaska .     do. 

Honolulu  Hawaiian  Islands. 

Tahiti Society  Islands. 

Levuka Fiji  Islands. 

Apia Samoan  Islands. 

Melbourne Australia. 

Port  Darwin do. 

Sydney do. 

Auckland New  Zealand. 

Wellington do. 


6.— RELATIONS  BET^W^EEN  THE   BAROMETRIC  PRESSURE  AND 
THE  STRENGTH  AND  DIRECTION  OP  OCEAN  CTJRRENTS. 

Lieut.  W.  H.  Bekhler,  U.  S.  Navy. 

The  student  of  ocean  meteorology  can  hardly  fail  to  notice  a 
striking  similarity  between  the  average  annual  curves  of  isobars  and 
the  general  circulation  of  the  main  currents  in  the  five  great  oceans. 

The  general  circulation  of  the  winds  around  the  almost  permanent 
centers  of  high  pressure  in  the  North  and  South  Atlantic,  the  North 
and  South  Pacific,  and  Indian  oceans,  deduced  from  observations  of 
wind  directions  extending  over  many  years,  has  been  demonstrated 
by  their  coincidence  with  the  curves  of  isobars  to  be  in  accordance 
with  the  first  principles  of  meteorology. 

There  is  a  most  intimate  relation  between  the  barometric  pressure 
and  the  wind  force  and  direction.  The  character  of  the  gradients  of 
barometric  pressure  is  the  best  evidence  of  the  force  of  the  wind,  and 
the  great  practical  value  of  the  barometer  to  mariners  consists  in  the 
feature  that  the  changes  in  the  barometer  readings  are  the  most 
reliable  of  all  the  indications  of  change  in  the  weather. 
12 


178  CHICAGO    METEOROLOGICAL   CONGRESS. 

The  North  Atlantic  Pilot  Chart  for  June,  1893,  has*  three  charts  of 
the  North  Atlantic,  the  main  chart  and  two  small  subcharts,  one  of 
which  is  a  chart  of  the  curves  of  isobars  and  isotherms  which  obser- 
vations of  many  years  indicate  to  be  the  normal  condition  for  the 
month  of  June,  and  the  other  is  a  chart  showing  the  average  annual 
set  of  the  surface  currents  of  the  North  Atlantic. 

Unfortunately  there  are  no  monthly  charts  of  the  currents,  but  the 
comparison  of  these  three  charts  suffices  to  invite  scientific  investi- 
gation of  this  coincidence  to  determine  if  there  be  any  law  governing 
the  relation  and  the  manner  and  effect  of  its  operations. 

I  submit  the  remarks  on  the  Pilot  Chart  in  relation  to  this  analogy 
between  the  movements  of  the  air  and  the  curves  of  equal  barometric 
pressure : 

The  strength  of  the  surface  currents  is  indicated  by  the  proportional  quantity  of  the 
arrows  on  the  chart.  The  greatest  number  of  arrows  are  drawn  where  the  currents  are 
strongest.  There  is  doubt  about  the  direction  and  strength  of  these  currents  in  certain 
parts  of  the  North  Atlantic,  and  our  voluntary  co-operating  observers  among  mariners 
of  all  nations  are  requested  to  continue  their  observations  to  ascertain  the  exact  set  and 
strength  of  surface  currents. 

In  the  Bay  of  Biscay  recent  investigations  indicate  that  the  Rennell  current,  as  shown 
on  the  main  chart,  setting  along  the  north  coast  of  Spain  east  to  the  coast  of  France, 
and  thence  north  and  north-northwest  athwart  the  current  setting  up  the  English  and 
Irish  channels,  does  not  exist,  at  least  during  the  summer  months;  but.  on  the  contrary, 
it  is  claimed  that  currents  set  in  a  south-southeasterly  direction  into  the  Bay  of  Biscay, 
and  thence  westward  along  the  north  coast  of  Spain.  No  doubt  there  is  a  large  volume 
of  water  from  the  Gulf  Stream  which  enters  the  Bay  of  Biscay  and  must  escape  and 
cause  surface  currents  to  set  out,  some  around  Brest  into  the  English  Channel,  and  some 
around  Cape  Finisterre  down  along  the  coast  of  Portugal,  the  set  depending  largely 
upon  the  direction  of  the  prevailing  wind. 

By  comparing  the  blue  wind  arrows  on  main  chart  with  the  small  barometer  chart 
and  the  small  current  chart,  a  striking  similarity  appears  between  the  curves,  showing 
equal  barometer  pressure,  directions  of  the  winds,  and  the  general  directions  of  the 
ocean  currents.  Among  the  causes  which  operate  to  produce  and  influence  the  winds 
and  currents,  this  comparison  suggests  that  the  varying  barometer  pressure  may  be  one 
of  the  original  causes  as  well  as  a  final  influence  on  the  direction  of  the  currents, 
directly  by  its  varying  pressure,  as  well  as  indirectly  through  its  relations  to  the  winds. 
To  what  extent  the  barometric  pressure  is  a  factor  in  influencing  ocean  currents  invites 
careful  observations.  The  strength  of  the  currents  depends  largely  on  the  contour  of 
the  coast,  as,  in  the  northwest  part  of  the  Caribbean  Sea,  where  the  w^ater  is  raised  by 
the  westerly  current,  and  flows  through  the  Strait  of  Yucatan  into  the  Gulf  of  Mexico, 
a  reservoir  which  discharges  through  the  Strait  of  Florida  and  gives  abnormal  strength 
to  that  part  of  the  current  system  of  the  North  Atlantic  known  as  the  Gulf  Stream. 

In  the  practical  presentation  of  meteorological  conditions  the  Pilot 
Charts  meet  the  purpose  for  which  they  are  published,  and  Lieut. 
Commander  Richardson  Clover,  ex-Hydrographer,  merely  intended 
to  invite  scientific  investigation  of  this  relationship  of  currents  to 
wind  and  barometric  pressure  with  the  hope  that  it  may  lead  to 
ascertain  truths  of  practical  application. 

The  late  Prof.  Wm.  Ferrel    published  a  number  of  letters  and 


BAROMETRIC    PRESSURE   AND    OCEAN    CURRENTS.  179 

articles  in  relation  to  ocean  currents  and  sea  level  in  Science  in 
1886,  and  he  concluded  that  the  wind  has  little  or  no  effect  in  pro- 
ducing ocean  currents.  These  articles  excited  considerable  attention, 
and  were  criticised  because  his  theories  on  the  ocean  currents  were 
based  upon  statements  in  regard  to  a  difference  of  one  meter  between 
the  sea  level  of  the  Gulf  of  Mexico  and  that  of  the  Atlantic  Ocean 
near  New  York. 

It  is  not  possible  in  the  limit  of  this  paper  to  enter  into  all  the 
details  of  the  discussion  of  the  causes  which  produce  ocean  currents. 
Prof.  Ferrel  advocated  the  difference  in  specific  gravity  between  cold 
Arctic  and  warm  tropical  water  as  the  chief  factor,  and  that  the  wind 
was  only  a  temporary  disturbing  or  a  locally  contributing  agent, 
while  Prof.  Newberry  admitted  the  gravitation  theory  as  a  cause  but 
a  less  effective  one  than  the  friction  of  the  wind. 

In  Croll's  Climate  and  Time  there  are  chapters  discussing  the  grav- 
itation theory  and  wind  theory  in  a  manner  which  might  be  supposed 
to  be  conclusive,  but  the  necessity  of  further  investigation  is  still 
apparent,  because  the  effect  of  differences  in  atmospheric  pressure 
was  overlooked. 

Naturally  mariners  have  been  practically  investigating  the  subject 
of  ocean  currents  more  than  scientists  who  do  not  go  to  sea,  and 
while  the  former  may  not  make  such  elaborate,  painstaking  researches 
and  calculations,  their  actual  experience  of  the  ocean  surface  cur- 
rents must  have  weight  as  well  as  statements  of  the  existence  of  cur- 
rents deduced  from  theory  alone. 

The  statement  that  the  wind  has  little  or  no  effect  in  producing 
surface  currents  can  not  stand  in  the  face  of  the  almost  universal  ex- 
perience that  currents  are  generally  found  setting  to  leeward  during 
and  after  a  gale,  excepting  when  in  a  well-known,  strongly-defined 
current  like  the  Gulf  Stream,  a  wind  blowing  against  that  current 
may  not  entirely  counteract  it,  but  will,  on  the  surface,  retard  its 
surface  velocity  and  cause  a  high,  rough  sea. 

Capt.  Hoffman,  of  the  German  Navy,  in  a  pamphlet  (Zur  Mechanik 
der  Meerestromungen  an  der  Oherjldche  des  Oceans,  Berlin,  1884)  brings 
out  the  value  of  the  wind  as  the  chief  motive  force,  and  shows  the 
inefficiency  of  gravity  due  to  difference  of  temperature  to  produce 
ocean  currents.  The  part  played  by  deflective  forces  due  to  the  earth's 
rotation  is  also  well  stated,  but  as  long  as  waters  are  brushed  along 
by  the  wind  in  any  direction  the  tendency  to  depart  from  that  direc- 
tion due  to  the  deflective  force  of  the  earth's  rotation  is  overcome, 
but  where  there  is  a  belt  of  calms  they  begin  to  describe  an  "inertia 
curve,"  a  line  whose  radius  of  curvature  decreases  with  the  sine  of  the 
latitude.  In  latitude  5°  this  radius  of  curvature  for  a  velocity  of  one 
meter  per  second  is  only  42|  miles,  hence,  when  the  South  Atlantic 
Current  runs  into  regions  north  of  the  equator,  its  waters  turn  to  the 


180  CHICAGO    METEOROLOGICAL    CONGRESS. 

right  and  form  the  Guinea  Current,  and,  during  the  northern  sum- 
mer, the  Equatorial  Counter  Current.  The  author  concludes  that 
the  winds  are  first,  then  configuration  of  coasts,  then  the  rotation  of 
the  earth,  and,  finally,  the  force  of  gravity  in  their  relative  influence 
to  produce  currents. 

The  wind  blows  horizontally  parallel  with  the  surface  of  the  sea, 
or  inclined  at  an  angle  either  upward  or  downward.  In  the  first 
case  the  parallel  motion  would  have  some  effect  by  its  friction,  and 
much  less  if  the  wind  be  upward,  but  where  inclined  downward  the 
downward  pressure  causes  a  depression  and  forms  a  ridge  of  water  in 
front  of  this  depression  which  offers  resistance  and  is  carried  along 
with  maximum  effect.  Where  waves  are  formed  the  crests  are  im- 
pelled along  by  the  wind  and  a  considerable  volume  of  surface  water 
is  necessarily  transported  by  the  wind.  To  what  extent  the  wind 
carries  the  surface  water  to  leeward  depends  upon  its  force  and  con- 
tinuance. In  cases  where  a  storm  wave  meets  the  sudden  resistance 
of  coast  line  the  shores  have  been  indundated  to  a  depth  of  from  20 
to  40  feet,  as  is  reported  in  the  account  of  the  six  typical  Bay  of  Ben- 
gal cyclonic  storms  in  the  "  Hand  Book  of  the  Cyclonic  Storms  in  the 
Bay  of  Bengal,"  published  by  the  Meteorological  Department  of  the 
Government  of  India. 

These  facts  appear  to  me  to  indicate  that  the  direction  of  ocean 
currents  is  most  frequently  to  leeward.  On  Berghaus'  Physical  Atlas 
No.  21,  Seestrdiiiu7igen,  the  ocean  currents  in  connection  with  the  areas 
of  the  permanent  high  air  pressure  in  the  different  oceans  are  indi- 
cated. The  wind  circulations  and  curves  of  isobars  are  here  also 
shown  to  coincide. 

The  analogy  between  the  curves  of  isobars  and  the  directions  of 
winds  and  currents  is  therefore  evident.  It  only  remains  to  demon- 
strate the  nature  of  this  relation  and,  if  possible,  reconcile  all  the 
theories  of  scientists  with  the  experience  of  mariners. 

The  most  effective  manner  in  which  the  wind  can  act  upon  the 
surface  waters  to  produce  a  current  is  where  it  is  inclined  downward, 
and  where  the  friction  of  the  moving  air  is  enhanced  by  its  pressure 
down  upon  the  water. 

Those  areas  of  high  pressure,  more  or  less  permanent  in  latitude 
28°  north  and  south,  must  necessarily  exert  by  their  weight  of  air  a 
greater  pressure  upon  the  water  upon  which  they  rest  than  lesser 
weights  of  air  in  areas  of  lower  pressure  exert  upon  the  water  in 
other  parts  of  the  ocean. 

The  differences  in  temperature,  differences  of  level, «,nd  rotation  of 
the  earth  must  combine  to  give  a  complicated,  unstable  resultant 
effect  of  this  atmospheric  pressure  upon  the  sea.  The  first  three  con- 
ditions may  be  in  operation,  but  the  varying  operation  of  the  atmos- 


BAROMETRIC    PRESSURE    AND    OCEAN    CURRENTS.  181 

pheric  pressure  must  cause  the  final  resulting  effect  upon  the  surface 
water. 

The  curves  of  isobars  around  the  "  high  "  on  opposite  sides  of  the 
equator  would  leave  the  equatorial  regions  with  less  weight  of  atmos- 
phere than  where  the  areas  of  high  pressure  exist. 

The  "  World's  Chart  of  Isobars  "  shows  that  there  is  a  normal  atmos- 
pheric pressure  on  both  sides  of  the  equator  from  about  N.  10°  to 
S.  10°.     This  pressure  is  760  mm.,  or  29.92  inches. 

The  area  of  normal  high  barometer,  30.16  inches,  southwest  of  the 
Azores,  is  about  700,000  square  miles,  and  the  weight  of  that  mountain 
of  air  is  227,000,000,000  tons  greater  than  the  weight  of  air  over  an 
equatorial  belt  of  equal  area  south  of  N.  10°,  where  the  barometer  is 
normal,  or  29.92  inches,  one-quarter  of  an  inch  lower  than  the  "  high." 

The  researches  of  the  Challenger  expedition  claim  to  have  estab- 
lished that  the  general  surface  of  the  North  Atlantic,  in  order  to 
produce  an  equilibrium  must  stand  at  a  higher  level  than  at  the 
equator.  I  claim  that  a  difference  of  level  must  be  the  difference  of 
effect  of  atmospheric  pressure.  The  pressures  under  the  areas  of  high 
barometer  would  make  those  areas  of  lower  level  than  the  equatorial 
regions,  but  the  section  of  the  Atlantic  examined  by  the  Challenger 
on  W.  40°,  and  between  N.  38°  and  S.  38°,  puts  the  higher  level  near 
the  extremities.  B}'  computing  the  effect  of  heat,  Dr.  Croll  states 
that  the  surface  level  at  N.  38°  is  3|  feet  higher  than  at  the  equator. 
But  the  Challenger  researches  did  not  consider  barometric  pressure 
as  a  cause  to  lower  the  sea  level.  Only  a  small  part  of  the  ocean  was 
examined,  and  it  is  probable  that  further  research  will  demonstrate 
that  the  lowest  level  of  the  ocean  is  under  the  area  of  the  highest 
barometric  pressure. 

The  isobars  at  about  N.  40°  show  that  the  pressure  there  is  the 
same  as  on  the  equatorial  belt.  The  gradients  north  of  40°  are 
steeper,  and  the  difference  of  level  should  be  greater.  In  the  North 
Atlantic  the  area  of  low  pressure  is  near  Iceland,  and  the  effect  of 
the  barometric  pressure  should  make  that  the  highest  level. ^ 

In  the  sketch  the  downward  pressure  of  the  atmosphere  in  the  *'  high  " 
and  its  upward  pressure  in  the  "low"  are  illustrated.  Manifestly  the 
enormous  difference  of  pressure  must  have  the  eft'ect  upon  the  incom- 
pressible water  to  push  it  away  from  the  region  of  the  "  high  "  to  that  of 
the  "  low." 

This  causes  variation  in  the  sea  level  and  surface  currents.  The 
true  final  direction  of  the  currents  must  be  in  the  direction  of  the 
resultant  of  the  force  of  atmospheric  pressure,  the  wind,  and  the  rota- 
tion of  the  earth.  Generally,  as  the  angle  which  these  first  two  forces 
make  with  each  other  is  small,  the  resultant  will  be  nearly  to  leeward. 
Its  strength  will  depend  upon  these  forces,  together  with  the  specific 
gravity  of  the  water,  the  time  the  forces  were  acting,  the  acquired 


182  CHICAGO    METEOROLOGICAL    CONGRESS. 

momentum,  the  pre-existing  condition  of  surface  whither  the  currents 
flow,  and  the  limiting  slope  of  the  raised  sea  level.  The  gradients  of 
high  barometric  pressure  are  constantly  varying  and  unequally  dis- 
tributed, the  pressure  acts  on  the  water  with  a  downward,  outward, 
spiral  motion  as  on  the  air,  and  currents  flow  with  the  wind  or  at  an 
angle  with  it,  depending  upon  conditions  of  surface  just  mentioned. 

The  investigations  of  the  Prince  of  Monaco  in  the  yacht  V Hirondelle, 
during  the  summers  of  1885  to  1888,  on  ocean  currents  show  a  much 
closer  analogy  between  the  curves  of  isobars  and  surface-water  circu- 
lation, especially  in  the  elliptical  movement  in  and  around  the  Sara- 
gossa  Sea.  The  Azores  are  shown  to  be  on  one  of  the  curves,  and  the 
drifts  of  the  U Hirondelle  floats  describe  ellipses  varying  in  diameter 
from  200  miles  to  the  coast  lines  on  both  sides  of  the  Atlantic.  The 
drifts  of  derelicts  and  thousands  of  ocean  current  reports  by  bottle 
papers  of  the  U.  S.  Hydrographic  Office  indicate  the  same  conformity 
of  surface  drift  with  the  curves  of  isobars. 

The  configuration  of  the  coast  line  has  an  effect  upon  the  circula- 
tion, and  the  explanation  quoted  from  the  June  Pilot  Chart  fully 
explains  the  abnormal  Gulf  Stream  Current. 

The  effect  of  the  barometric  pressure  on  the  Gulf  Stream  has  been 
well  established,  and  in  Lieut.  Pillsbury's  report  on  "Gulf  Stream 
Investigations  and  Results,"  there  is  one  chapter  devoted  to  the  cause 
of  the  Gulf  Stream  and  of  Atlantic  currents.  After  a  very  thorough 
examination  of  the  gravity  and  wind  theories,  he  advocates  the  wind 
theory  as  the  principal  cause,  but  in  the  closing  pages  of  the  chapter 
he  explains  abnormal  currents  by  the  effect  of  barometric  pressure. 
He  states  that  a  difference  of  one  inch  in  the  barometric  column,  or 
about  half  a  pound  in  atmospheric  pressure,  will  give  over  one  foot 
difference  in  the  elevation  of  the  surface  of  the  sea. 

The  chart  of  isobars  for  the  year  shows  that  there  is  a  region  in 
the  North  Atlantic  between  about  N.  10^  and  N.  40°  of  about  9,600,000 
square  miles  where  the  barometric  pressure  is  above  the  normal,  29.92 
inches,  760  mm.  North  of  this  zone  there  is  an  area  of  ocean  surface 
of  about  2,300,000  square  miJes  where  the  pressure  is  below  the 
normal. 

The  maximum  high  is  about  30.16  inches  and  the  minimum  low  is 
29.69  inches,  or  a  difference  of  about  0.47  of  an  inch.  If  one  inch  in 
the  height  of  the  barometer  represents  about  half  a  pound  in  the  atmos- 
pheric pressure  per  square  inch,  the  total  difference  of  the  weight  of 
atmosphere  upon  these  regions  reaches  an  enormous  figure,  sufficient 
to  cause  a  very  decided  difference  between  the  levels  of  the  sea  at  the 
areas  of  the  maximum  high  and  minimum  low.  (This  difference,  I 
believe,  amounts  to  about  20  meters.)  The  surface  water  will  be 
forced  up  an  incline  in  the  region  of  the  "low."  The  lack  of  pressure, 
or  rather  the  diminished  air  pressure  in  the  low  region  taken  in  con- 


Plate  ^Vll* 


Beehler. 


BAROMETRIC    PRESSURE    AND   OCEAN    CURRENTS.  183 

nection  with  the  lesser  area,  will  still  farther  enhance  the  accumula- 
tion of  the  water  in  the  region  of  the  "  low." 

The  atmospheric  pressure  in  the  Atlantic  causes  the  accumulation 
in  the  western  part  of  the  Caribbean  Sea,  and  the  sea  level  there 
and  in  the  Gulf  of  Mexico  is  one  meter  higher  than  that  off  Sandy 
Hook,  N.  Y. 

The  Gulf  Stream,  thus  formed,  unites  with  the  waters  of  the  At- 
lantic circulating  around  the  "  high "  and  flowing  up  along  the 
Bahamas  and  following  the  United  States  coast  line  to  Hatteras.  The 
waters  continue  on,  but  after  passing  the  Grand  Banks  they  meet 
with  no  further  coast  resistance  and  are  pushed  out  by  the  barometric 
pressure,  which  is  constantly  diminishing,  into  the  Arctic  until  the 
upward  slope  is  so  great  that  the  diminishing  pressure  can  no  longer 
force  the  water  there.  A  large  volume  of  water  flows  down  between 
the  Azores  and  the  coasts  of  Portugal  and  Africa,  where  the  pressure 
is  less  than  the  maximum,  and  then  continues  circulating  around  as 
before. 

The  water  thvis  continually  pressed  away  by  the  high  pressure  from 
the  mid  North  Atlantic  must  be  replaced,  and.  consequently  there  are 
undercurrents  of  cold  water  from  the  Arctic  and  northern  part  of  the 
North  Atlantic  to  restore  the  equilibrium.  These  cold  currents  will, 
on  account  of  their  specific  gravities,  fall  below  the  warmer  surface 
currents,  and  while  this  barometric  pressure  is  acting,  these  cold  cur- 
rents flowing  south  cannot  appear  on  the  surface,  for  if  they  did 
appear  they  would,  under  normal  conditions,  be  necessarily  brushed 
back  again  toward  the  Arctic. 

Where  the  configuration  of  the  coasts  has  deflected  this  circulation 
of  water  away  from  the  shores,  the  cooler  currents  may  there  appear 
on  the  surface,  and,  consequently,  we  find  a  cold  current  from  the 
Arctic  along  the  coast  of  Labrador,  sneaking  in  around  Newfound- 
land and  close  along  the  United  States  coast  to  Hatteras  and  Florida. 

In  the  report  for  1891,  Appendix  No.  10,  of  the  U.  S.  Coast  and 
Geodetic  Survey,  Prof.  E.  E.  Haskell  publishes  an  account  of  obser- 
vations of  currents  in  the  Straits  of  Florida  and  Gulf  of  Mexico,  and 
on  page  347  he  states : 

Over  a  water  surface  unequal  atmospheric  pressure  and  wind  both  become  causes, 
acting  generally  at  an  angle  with  each  other  to  produce  a  current.  The  former  is  the 
equivalent  of  a  head  to  be  spent  as  a  gravity  force  in  the  direction  of  the  trend  of  the 
barometric  gradient,  while  the  latter  acts  by  friction  on  the  surface  to  produce  a  current 
in  its  direction.  There  is  little  or  no  information  extant  as  to  the  current  that  any 
known  velocity  of  wind  and  barometric  gradient  will  produce,  nor  is  there  a  definite 
enough  relation  between  direction  of  wind  and  trend  of  barometric  gradient  to  permit  of 
making  more  than  the  general  statement  that  the  current  should  be  in  the  direction  of 
the  resultant  of  the  two  forces. 

I  quote  this  by  permission,  and  this  pamphlet  contains  tables  con- 
necting the  observations  of  currents  with  meteorologic  data.     I  also 


184  CHICAGO    METEOROLOGICAL   CONGRESS. 

have  in  a  letter  from  Prof.  Haskell  the  further  statement  that,  "  If  I 
had  at  my  command  daily  observations  of  the  direction  and  force  of 
the  wind  and  the  reading  of  the  barometer  from  stations  so  located  as 
to  surround  the  Gulf,  I  could  predict  the  currents  much  as  our  weather 
is  predicted." 

In  investigating  the  ocean  currents  it  must  be  remembered  that  the 
mountain  of  air  in  the  region  of  the  almost  permanent  "  high  "  is  not 
constant  in  extent  or  in  exact  locality.  I  have  taken  the  average 
annual  location  and  direction  of  the  areas  of  the  "  high  "  in  the  North 
Atlantic.  This  varies,  and  the  Pilot  Chart  for  each  month  shows 
these  variations  graphically.  Again,  near  the  belt  of  normal  atmos- 
pheric pressure  the  air  circulation  around  the  "  high  "  is  accompanied 
by  other  circulations,  both  cyclonic  and  anticyclonic,  and  these  storms 
will  temporarily  disturb  the  normal  condition  and  cause  variations 
in  the  current  both  in  strength  and  direction. 

To  follow  the  movement  of  a  cyclonic  circulation  across  the 
Atlantic  toward  Europe  and  the  Arctic  the  waters  under  the  center 
must  be  relieved  of  pressure  by  the  extent  of  the  abnormal  difference 
of  air  pressure.  The  winds  also  in  the  cyclonic  circulation  flow  in, 
around,  and  upward,  and  these  causes  must  contribute,  not  only  to 
raise  the  level  of  the  surface  water,  but  also  to  make  this  increase  of 
level  to  take  place  in  a  comparatively  small  circular  space ;  hence, 
the  remarkable  high,  almost  vertical,  seas  which  are  raised  and  fall 
with  such  destructive  effect  all  around  in  a  confused  mass  in  the 
center  of  a  cyclone. 

The  storm  waves  quoted  from  the  Bay  of  Bengal  typical  cyclones 
are  explained  on  this  theory,  and  further  examples  might  be  quoted 
to  show  that  the  currents  of  all  oceans  and  at  all  times  are  chiefly  due 
to  the  atmospheric  pressure.  Our  knowledge  of  the  ocean  currents  is 
far  from  exact,  and  the  object  of  this  paper  is  to  invite  investigation 
of  the  subject  of  ocean  currents  in  connection  with  the  barometric 
pressure. 

It  is  extremely  difficult  to  ascertain  the  direction  and  strength  of 
ocean  currents.  As  a  rule  the  reports  of  currents  experienced  are 
really  the  difference  between  an  estimated  run  of  a  ship  in  twenty- 
four  hours  by  dead  reckoning  and  the  more  exact  run  as  determined 
by  astronomical  observations.  All  the  errors  of  the  estimated  course 
and  distance  made  good  for  twenty-four  hours  are  added  and  ascribed 
to  currents  which,  for  half  the  time,  may  have  been  in  one  direction  at 
one  rate  and  at  other  times  in  other  directions  at  different  rates. 

With  the  sextant  it  is  rare  that  a  captain  can  determine  his  posi- 
tion more  than  once  in  twenty-four  hours,  and  until  he  has  means  of 
finding  his  position  accurately  at  sea  more  frequently,  the  reports  of 
currents  experienced  will  be  unreliable. 

I  have  recently  invented  a  nautical  instrument,  the  solarometer, 


FLUCTUATIONS    OF    STORM    TRACKS.  186 

by  which  a  vessel's  exact  position  can  be  determined  at  sea  at  any 
time  of  day  or  night  that  any  heavenly  body  is  visible  in  the  sky, 
independent  of  the  visibilit}^  of  the  sea  horizon  and  without  any 
elaborate  calculations. 

The  speed  of  the  ship  through  the  water  being  measured  every  hour 
by  the  patent  log,  and  the  exact  geographical  position  being  deter- 
mined by  the  solarometer  every  hour,  the  difference  between  the 
speed  through  the  water  and  that  made  good  over  the  ground  will  be 
the  amount  of  current  experienced. 

It  is  difficult  to  estimate  the  importance  of  a  full  and  complete  in- 
vestigation of  this  relationship  of  the  barometer  to  the  ocean  cur- 
rents. If  the  investigations  demonstrate  the  exact  character  of  the 
relations  it  may  be  possible  for  a  mariner  to  see  from  one  or  more 
observations  of  the  currents  and  the  readings  of  the  barometer  the 
meteorologic  conditions  of  a  wide  range  over  the  ocean.  Or,  having 
barometer  readings  and  meteorologic  conditions,  he  may  predict 
currents. 

There  is,  of  course,  a  certain  amount  of  momentum  to  be  overcome 
to  cause  a  current,  and  an  element  of  time  would  have  to  be  consid- 
ered, but  investigation  of  the  subject  will  doubtless  reveal  much  of 
the  mystery  with  which  it  is  now  connected. 

To  the  science  of  meteorology  the  subject  is  one  of  the  most  im- 
portant. The  influence  of  the  Gulf  Stream  and  of  the  tropical 
waters  which  circulate  with  the  Gulf  Stream  around  the  region  of 
the  almost  permanent  "  high,"  upon  the  climate  of  Europe,  and  similar 
influences  of  like  circulations  on  all  five  oceans  all  over  the  world, 
upon  the  climate  of  these  regions  are  secondary  to  no  other  meteoro- 
logic phenomenon.  Exact  knowledge  of  the  direction  and  strength 
of  the  ocean  currents  so  determined  will  be  of  incalculable  benefit 
to  commerce  and  mankind. 


7.— PERIODIC  AND  NON-PERIODIO  FLUCTUATIONS  IN  THE  LAT- 
ITUDE OF  STORM  TRACKS, 

Dr.  M.  A.  Veeder. 

There  are  certain  rearrangements  in  the  distribution  of  atmos- 
pheric pressure  of  world-wide  extent  which,  at  times,  continue 
throughout  entire  seasons,  or  even  for  series  of  years,  and  which, 
likewise  at  times,  appear  irregularly  and  sporadically  at  individual 
dates,  which  evidently  must  depend  upon  some  cause  capable  of 
affecting  the  entire  earth.  The  most  prominent  feature  in  such 
rearrangement  is  a  displacement  in  latitude  of  the  belts  of  anti- 
cyclones on  each  side  of  the  equator  with  consequent  deflection 
northward  or  southward,  as  the  case  may  be,  of  the  courses  taken  by 


186  CHICAGO    METEOROLOGICAL   CONGRESS. 

storms  prevailing  at  such  times.  A  very  notable  instance  of  one 
species  of  such  displacement  occurred  in  1877-'78,  when  anticyclonic 
weather  conditions  were  very  persistent  in  low  latitudes,  as  evidenced 
by  the  extraordinary  extent  and  severity  of  the  droughts  which  belted 
the  entire  earth  in  the  equatorial  regions.  Coincidently,  the  diver- 
sion of  storm  tracks  into  higher  latitudes  was  shown,  especially  by 
the  phenomenal  mildness  of  the  winter  seasons.  Ten  years  later,  in 
1888-'89,  there  was  a  repetition  of  these  same  characteristic  features 
dependent  upon  atmospheric  distribution.  In  this  instance  the 
mildness  of  the  winter  season,  particularly  that  of  1889-'90,  seems  to 
have  extended  even  into  the  Arctic  regions,  causing  floating  ice  to 
appear  off  the  coast  of  Labrador  and  Newfoundland  in  great  quanti- 
ties throughout  months  in  which  it  is  rarely  seen  at  all  in  that  loca- 
tion. At  the  same  time  on  the  North  American  continent  there  was 
a  marked  deficiency  in  the  severity  and  extent  of  cold  waves,  and 
storm  tracks  had  their  centers  far  north  for  extended  periods.  The 
same  mildness  appeared,  likewise,  in  the  northern  parts  of  the 
eastern  hemisphere,  while  in  India,  on  the  other  hand,  anticyclonic 
conditions  predominated,  there  being  "  a  general  rise  of  abnormal 
barometric  pressure  for  a  considerable  period  *  *  *  and  scanty 
rainfall  throughout  the  year."     {Nature^  June  5,  1890,  p.  134.) 

It  is  not  within  the  province  of  a  brief  summary,  such  as  the  pres- 
ent, to  do  more  than  indicate  leading  features.  Suffice  it  to  say  that 
the  extraordinary  persistence  and  extent  of  the  distribution  of  the 
types  of  weather  described  in  the  years  named  is  not  only  in  strong 
contrast  to  average  conditions,  but  is  in  still  greater  contrast  to  those 
prevailing  in  years  when  the  divergence  from  the  normal  is  in  an 
opposite  direction,  anticyclones  with  greater  dryness  and  stronger 
cold  waves  prevailing  in  higher  latitudes,  with  corresponding  dis- 
placement of  cyclonic  weather  conditions  into  different  and,  for  the 
most  part,  lower  latitudes.  The  present  year  affords  an  example  of 
this  variety  of  divergence  from  the  normal,  both  in  this  country  and 
Europe,  the  winters  in  northern  latitudes  being  distinguished  by  a 
severity  in  strong  contrast  to  their  mildness  during  the  years  pre- 
viously named,  and  the  areas  distinguished  by  phenomenal  droughts 
during  the  summer  likewise  being  transferred  to  higher  latitudes 
with  coincident  strengthening  of  the  storms  and  hurricanes  of  low 
latitudes.  In  this  connection  it  is  worthy  of  note  that  what  is 
thought  to  have  been  the  lowest  reading  of  the  barometer  ever  re- 
corded on  the  Atlantic  was  met  with  during  a  storm  far  south  last 
December.  So,  too,  the  West  Indian  hurricane  season  now  approach- 
ing promises  to  be  severe.  Coincidently,  complaints  of  droughts  are 
heard  from  the  interior  of  the  North  American  continent  and  from 
the  north  of  Europe,  Great  Britain,  especially,  suffering  severely.  In 
order  to  bring  out  completely  these  contrasts  in  weather  conditions 


FLUCTUATIONS    OF   STORM    TRACKS.  187 

it  would  be  necessary  to  consider  in  detail  the  effect  of  rearrange- 
ments in  the  distribution  of  atmospheric  pressure  upon  rainfall, 
cloudiness,  temperature,  the  direction  and  force  of  the  winds,  and 
the  like,  not  only  at  different  seasons  of  the  year,  but  also  in  partic- 
ular localities,  which,  manifestly,  is  a  task  of  considerable  magnitude. 
But  without  entering  thus  into  detail  it  is  sufficiently  evident  for  the 
purposes  of  the  present  discussion  that  the  distribution  of  cyclonic 
and  anticyclonic  weather  conditions  throughout  the  globe  varies  in 
different  years  in  the  manner  which  has  been  described.  The  broad 
features  of  these  types  of  weather  are  readily  distinguishable,  both  on 
land  and  sea  and  in  summer  and  winter,  under  all  the  modifications 
which  they  thus  undergo,  so  that  their  transference  from  one  latitude 
to  another  can  be  traced  with  a  good  degree  of  confidence.  Indeed 
such  transference  and  localization  of  weather  types  through  more  or 
less  extended  periods  is  one  of  the  most  striking  and  familiar  facts  of 
meteorological  observations. 

In  like  manner,  for  brief  intervals,  there  may  intervene  strongly 
marked  but  relatively  transient  divergences  from  the  more  persistent 
types  of  weather  prevailing  in  the  manner  which  has  been  described. 
Thus,  upon  some  particular  date,  anticyclones  may  suddenly  appear  in 
higher  latitudes  than  that  which  they  had  been  accustomed  to  fre- 
quent for  weeks  or  mouths  preceding,  and  begin  to  move  eastward 
with  more  activity  and  become  stronger,  the  storms  prevailing  along 
their  peripheries  being  modified  likewise  in  respect  to  the  courses 
which  they  pursue  and  the  energy  which  they  display.  In  such  cases 
an  impulse  of  some  sort  appears  to  have  been  imparted  suddenly  to 
the  atmosphere,  as  a  whole,  the  increased  rapidity  of  eastward  move- 
ment and  intensification  of  storm  action  being  apparent  in  the  case 
of  all  cyclones  and  anticyclones  prevailing  at  the  time.  Thus,  in- 
stances have  been  noted  in  which  storms  in  America  and  Europe,  and 
off  the  coast  of  Japan,  have  acquired  phenomenal  intensity  on  the 
same  day,  constituting  a  well-defined  period  during  which  the  energy 
of  atmospheric  movements  was  largely  increased,  anticyclones  as  well 
as  cyclones  being  everywhere  strengthened.  In  such  cases  as  these 
there  does  not  appear  to  be  any  delay,  such  as  would  be  required  if 
the  increased  activity  displayed  were  dependent  upon  any  slow  pro- 
cess of  warming  up  continents  or  seas.  On  the  contrary  the  re- 
arrangement in  the  distribution  of  atmospheric  pressure  (and  inci- 
dental storm  action)  begins  promptly  and  in  such  manner  as  to  in- 
dicate that  its  origin  is  not  dependent  upon  local  terrestrial  condi- 
tions, the  part  performed  by  such  conditions  being,  apparently,  to 
modify  rather  than  originate  the  activities  in  question. 

Thus,  there  are  in  general  rearrangements  in  weather  conditions  so 
well  defined,  and  upon  such  a  large  scale,  that  it  is  difficult  to  resist 
the  conclusion  that  the  atmosphere,  as  a  whole,  is  under  the  control 


188  CHICAGO    METEOROLOGICAL    CONGRESS. 

of  forces  which  have  a  common  origin  and  which  undergo  variations 
at  their  very  seat  of  origin.  It  would  seem  that  it  ought  to  be  possi- 
ble to  determine  to  the  best  advantage  the  nature  and  mode  of  opera- 
tion of  such  forces  by  a  careful  study  of  the  instances  in  which  the 
divergences  from  the  normal  are  greatest.  For  several  years  the 
writer  has  been  collecting  information  bearing  upon  this  point,  the 
outcome  being  the  conclusion  that  the  divergences  in  question  must 
depend  ultimately  upon  some  form  of  solar  variability,  it  being  con- 
ceded on  all  hands  that  the  sun  is  the  great  source  of  atmospheric 
control.  As  to  the  essential  nature  of  this  variability  there  is,  how- 
ever, a  question.  From  current  views  respecting  atmospheric  con- 
trol, we  should  naturally  expect  it  to  consist  in  variation  in  the  sun's 
power  of  emitting  heat.  It  is  true  that  the  weather  conditions  to 
which  attention  has  been  called  present  anomalies  in  respect  to  tem- 
perature, but  these  have  reference  to  distribution  rather  than  total 
amount.  Thus,  investigators  using  data  from  different  parts  of  the 
earth  have  reached  precisely  opposite  conclusions  as  to  whether  the 
sun  is  hotter  or  colder,  and  that,  too,  in  the  very  years  in  which  the 
departures  from  the  normal  of  the  kind  indicated  have  been  largest. 
In  like  manner,  if  averages  are  taken  from  a  sufficiently  large  part  of 
the  earth,  the  variation  of  temperature  from  year  to  year  is  insig- 
nificant. So,  too,  the  exposure  of  properly  guarded  thermometers  to 
the  direct  rays  of  the  sun  in  localities  best  adapted  for  such  experi- 
ments, and  under  the  most  suitable  conditions,  has  thus  far  given  no 
evidence  of  variations  in  the  sun's  power  of  heat  emission  adequate 
to  explain  the  facts  to  which  reference  has  been  made.  It  is  a  ques- 
tion, indeed,  whether  variation  in  the  amount  of  heat  falling  upon 
the  earth,  as  a  whole,  could  produce  the  diversified  local  effects  appar- 
ent and  maintain  them  in  the  manner  which  actually  appears.  As  a 
matter  of  fact,  however,  it  is  not  yet  known  whether  the  sun  is  hotter 
or  colder  when  freest  from  spots.  The  observations  thus  far  made 
agree,  however,  in  showing  that  the  interposition  of  the  atmosphere 
and  its  contents,  and  especially  of  the  aqueous  vapor  which  it  con- 
tains, modifies  the  transmission  and  radiation  of  heat  to  such  an  ex- 
tent that  this  and  not  solar  variability  may  be  the  source  of  the 
changes  in  temperature  distribution  to  which  reference  has  been 
made.  This  being  the  case,  these  temperature  anomalies  are  to  be 
regarded  as  a  mere  incident  in  the  rearrangement  of  atmospheric  dis- 
tribution rather  than  its  cause.  Thus  it  becomes  necessary  to  look 
elsewhere  than  to  variations  in  the  heat-giving  power  of  the  sun  for 
the  source  of  atmospheric  control.  At  this  point  and  in  this  connec- 
tion a  relation  of  the  weather  conditions  described  to  the  distribution 
in  latitude  of  the  spots  on  the  sun  becomes  of  very  great  interest.  It 
is  found  that  the  fluctuation  in  latitude  of  the  belts  of  anticyclones 
on  the  earth  and  consequent  diversion  of  storm  tracks  to  which  refer- 


FLUCTUATIONS    OF    STORM    TRACKS.  ^        189 

ence  has  been  -made  follows,  and  is  in  direct  proportion  to  a  like 
change  in  latitude  of  the  belts  in  which  spots  are  most  frequent  on 
the  sun ;  that  is  to  say,  in  years  in  which  spots  appear  in  high  lati- 
tudes, anticyclones  do  likewise,  and  vice  versa.  The  transient  and 
irregular  deviations  from  this  order  constitute  a  case  by  themselves, 
and  are  to  be  studied  in  connection  with  the  evidences  of  spasmodic 
outbreaks  of  solar  activity  on  the  one  hand,  or  the  fitful  intervals  of 
solar  quiet  on  the  other,  which  may  interrupt  the  regular  order  of 
events  in  progress  in  any  particular  year  or  series  of  years. 

The  purpose  of  the  present  discussion  is  not  to  enter  very  much 
into  the  details  of  the  evidence,  which  would  be  impossible  within 
the  limits  assigned,  but  rather  to  indicate  in  a  general  way  the  nature 
of  the  problems  involved  as  an  incitement  to  further  research.  In 
the  judgment  of  the  writer,  based  upon  such  study  as  he  has  been 
able  to  make,  there  is  ground  for  the  belief  that  there  are  special 
forms  of  solar  activity,  not  as  yet  perhaps  fully  identified,  and  cer- 
tainly not  as  yet  fully  understood,  which  exercise  powerful  terrestrial 
effects  independently  of  any  perceptible  attendant  variation  in  the 
amount  of  solar  heat  falling  upon  the  earth  as  a  whole.  In  brief, 
these  special  solar  activities  appear  to  be  of  the  nature  of  electro- 
magnetic induction,  which  may  be  attended  by  incidental  heating 
effects,  it  is  true,  but  these  effects  have  a  different  distribution  and 
depend  upon  conditions  altogether  unlike  those  which  exist  in  the 
case  of  simple  radiation  from  a  source  of  combustion.  Temperature 
distribution  in  the  case  of  electro-magnetic  induction  depends  upon 
the  direction  assumed  by  lines  of  force  in  a  magnetic  field,  thus  con- 
stituting a  special  form  of  radiant  energy  having  characteristics 
essentially  different  from  those  manifest  in  the  case  of  heat  or  light. 
From  this  point  of  view  the  manner  of  recurrence  of  auroras  and 
magnetic  storms  and  their  relation  to  disturbances  upon  particular 
parts  of  the  sun  become  an  important  subject  of  research,  as  afford- 
ing the  means  of  acquiring  a  knowledge  of  the  limitations  under 
which  electro-magnetic  inductive  effects  are  conveyed  from  sun  to 
earth.  Especially  important  is  the  evidence  that  these  effects  are 
propagated  at  a  definite  angle,  originating  a  periodicity  of  magnetic 
phenomena  corresponding  to  the  time  of  a  synodic  rotation  of  the 
sun,  thus  differing  again  from  heat  radiation  which  proceeds  from  the 
sun  indifferently  in  every  direction,  and  not  at  a  certain  angle  exclu- 
sively. The  determination  of  the  solar  meridian,  or  in  other  w^ords, 
the  angle  at  which  the  inductive  effect  is  exercised  is  of  the  utmost 
importance. 

The  tables  constructed  by  the  writer  for  the  purpose  of  such  deter- 
mination are  very  voluminous,  covering  nearly  all  lists  of  auroras 
in  existence  and  very  extensive  records  of  magnetic  storms  and  sun 
spots.     The  practical  outcome  is  that  the  inductive  effect  proceeds 


190  CHICAGO    METEOROLOGICAL   CONGRESS. 

chiefly,  if  not  exclusively  from  disturbed  portions  of  the  sun  when 
at  the  eastern  limb,  and  that  such  effect  may  at  times  originate  thun- 
derstorms instead  of  auroras,  the  substitution  of  one  or  the  other 
of  these  two  classes  of  phenomena  depending  apparently  upon  the 
location  of  the  originating  solar  disturbance  relative  to  the  plane  of 
the  earth's  orbit  when  at  the  eastern  limb.  There  is  evidence  also  of 
a  terrestrial  localization  of  these  phenomena,  dependent  in  part,  ap- 
parently, upon  the  physical  conditions  existing  at  the  time  in  various 
parts  of  the  earth,  and  in  part  upon  a  concentration  of  effect  at 
certain  hour  angles  from  the  sun.  Thus,  there  are  diurnal  maxima 
and  secondary  maxima  both  of  thunderstorms  and  auroras,  and  the 
regions  frequented  by  them  have  a  belt-like  distribution  in  magnetic 
latitude.  From  this  it  appears  that  the  lines  of  force  along  which  the 
inductive  effect  proceeds  have  a  very  definite  arrangement,  and  that 
there  are  modifications  of  effect  in  particular  portions  of  the  field 
which  these  lines  occupy,  giving  rise  to  thunderstorms  instead  of 
auroras,  or  vice  versa,  as  the  case  may  be.  It  would  seem  that  the 
origin  of  the  whole  process  is  through  electrification  of  particular  por- 
tions of  the  sun's  immediate  surroundings  through  the  agency  of  the 
turmoil  of  chemical  and  other  activities  due  to  the  special  violence  of 
the  eruptive  forces  there  in  operation,  as  compared  with  the  rest  of 
the  sun,  and  that  the  inductive  effect  is  propagated  outward  into 
space  from  these  sections  of  the  sun  dynamically,  or,  in  other  words, 
in  virtue  of  the  motion  of  rotation. 

The  dynamic  origination  of  electrical  currents  has  been  greatly 
familiarized  of  late  by  the  commercial  applications  of  the  principle 
now  in  ordinary  use  for  many  purposes.  Such  origination  depends 
upon  a  very  different  set  of  conditions  from  those  involved  in  thermo- 
electric action  to  which  these  forms  of  solar  activity  have  generally 
been  referred  heretofore.  There  is  no  evidence  whatever  that  a  mag- 
netic storm  is  allied  to  or  dependent  upon  heat  radiations  in  any 
sense  or  to  any  extent  whatever.  Its  method  of  origination  and 
propagation  is  quite  different  in  every  respect,  and  any  heating  effects 
that  may  attend  are  incidental  and  remote.  Thus  there  is  a  form  of 
solar  activity  having  its  own  distinguishing  characteristics  and  exist- 
ing as  an  entity  by  itself  which  deserves  most  careful  study.  The 
earth  certainly  is  comprehended  within  the  range  of  its  operation, 
and  it  is  altogether  likely  that  the  inductive  effects  thus  experienced 
extend  throughout  the  entire  solar  system,  reaching  every  particle  of 
meteoric  dust  and  debris,  and  the  vapors,  if  such  there  be,  in  inter- 
planetary space,  as  well  as  the  planets  themselves.  All  these  masses 
of  matter  charged  up  by  induction  exhibit  permanent,  subpermanent, 
and  temporary  effects,  in  accordance  with  which  they  act  and  react 
upon  each  other  and  likewise  upon  the  sun  itself,  in  conformity  with 
the  laws  governing  induction. 


FLUCTUATIONS    OF    STORM    TRACKS.  191 

In  the  judgment  of  the  writer  it  is  the  reactionary  effect  upon  the 
6un  itself  of  these  inductive  forces,  causing  rearrangements  in  the 
distribution  of  the  vapors  in  its  vicinity,  as  seen  during  eclipses,  that 
determines  the  formation  of  spots  and  their  varying  location  in  lati- 
tude in  a  manner  altogether  similar  to  that  seen  in  connection  with 
the  coincident  changes  in  latitude  of  the  belts  of  anticyclones  on  the 
earth.  In  any  event,  the  fact  that  these  rearrangements  of  the 
vaporous  surroundings  of  sun  and  earth  undergo  similar  variations 
in  respect  to  location  in  corresponding  years  points  to  community  of 
origin  of  these  effects,  and  their  evident  relation  to  magnetic  phe- 
nomena of  the  sort  which  has  been  described  is  such  that  it  would 
seem  not  unwise  to  shift,  if  necessary,  the  point  of  view  for  the  con- 
sideration of  the  entire  subject,  and  to  attack  the  problems  at  issue 
along  the  lines  indicated  in  this  discussion.  This  involves  nothing 
less  than  a  reconsideration  of  every  fact  and  conclusion  in  respect  to 
meteorological  science  from  a  standpoint  altogether  different  from 
an  assumed  variability  of  solar  heat. 

It  may  be  necessary  to  go  so  far  as  even  to  discard  provisionally 
and  tentatively  the  convection  theory  of  the  origin  of  storms,  as 
ordinarily  held,  in  order  to  determine  fairly  and  completely  the  part 
which  electro-magnetic  induction  of  solar  origin  plays  independently 
of  heating  effects.  The  distribution  of  temperatures,  both  in  a  hori- 
zontal and  in  a  vertical  direction  in  cyclones  and  anticyclones,  and 
the  velocity  and  extent  of  the  associated  wind  movements,  likewise 
in  a  horizontal  and  vertical  direction,  are  not  easy  of  explanation  in 
conformity  with  the  convection  theory  of  the  origin  of  storms. 
Thus,  in  tropical  hurricanes,  where  the  violence  of  the  wind  move- 
ment is  extreme,  the  temperature  gradient  is  small.  Again,  in  the 
case  of  a  severe  storm  remaining  stationary  like  the  New  York  bliz- 
zard, it  would  seem  that  the  gravitational  inflow  of  such  enormous 
masses  of  air  ought  to  involve  a  filling  up  process.  Certainly,  current 
views  respecting  the  forces  concerned  in  storm  action  do  not  give  the 
slightest  intimation  as  to  where  all  the  air  goes  in  such  a  case  as  this. 

In  view  of  such  facts  as  these,  and  without  multiplying  further 
illustrations,  it  would  seem  to  be  not  only  reasonable  but  necessary 
to  institute  an  inquiry  as  to  whether  forces  other  than  those  hereto- 
fore taken  into  the  account  are  not  concerned.  To  this  end  especially 
important  is  the  identification  of  the  solar  and  other  conditions  on 
which  auroras  and  magnetic  storms  depend,  growing  out  of  which 
there  comes  an  apparent  relation  to  thunderstorms.  By  the  aid  of 
the  clue  thus  obtained  it  becomes  possible  to  study  the  behavior  of 
the  atmosphere  on  critical  dates,  and  during  critical  periods,  whose 
identification  is  secured  through  a  knowledge  of  these  solar  and  asso- 
ciated conditions.  As  has  been  intimated  throughout  the  course  of 
the  discussion  the  fluctuation  in  latitude  of  anticjxlonic  belts  and 


192  CHICAGO    METEOROLOGICAL    CONGRESS. 

storm  tracks  both  on  the  grandest  possible  scale,  as  affecting  climate 
through  series  of  years,  and  in  individual  instances  on  single  dates, 
is  most  likely  to  afford  an  insight  into  the  meteorological  relations 
of  electro-magnetic  forces  of  solar  origin.  These  forces  certainly 
play  a  part  in  the  economy  of  the  solar  system,  and  there  are  indica- 
tions that  this  part  is  far  more  important  than  has  heretofore  been 
supposed. 


8.  — NORTH   ATLANTIC   CXJBRENTS  AND   SURFACE   TEMPERA- 
TURES. 

Lieut.  A.  Hautrkux,  French  Navy. 

It  is  impossible  to  speak  of  meteorology  or  the  physical  geography 
of  the  sea  without  the  spirit  of  the  immortal  name  of  Lieut.  Maury. 
He  it  was  who  systematized  the  best  manner  of  making  observations 
and  enunciated  the  principles  and  general  laws  of  the  circulation  of 
the  atmosphere  and  the  oceans  to  the  scientific  world.  In  his  school 
this  science  has  been  studied,  and  especially  in  the  United  States, 
where  it  has  been  most  developed  on  land  and  sea. 

It  is  in  that  vast  country,  washed  by  two  oceans,  possessing  both 
tropical  and  polar  climates,  the  highest  mountains  and  most  exten- 
sive plains,  rainless  deserts  and  the  most  fertile  regions,  with  coasts 
washed  by  the  greatest  oceanic  river  in  the  world  and  annually  re- 
ceiving glacial  tributes  from  Greenland — it  is  there  where  the  ele- 
ments of  heat  and  cold,  dryness  and  moisture,  rage  and  produce  with 
greatest  force  the  phenomena  caused  by  the  conflict.  There  the 
science  of  meteorology,  based  upon  actual  observations,  has  made 
the  greatest  progress.  There,  also,  the  public  is  most  promptly  noti- 
fied and  warned  of  meteorological  disturbances,  and  measures  taken 
to  prepare  for  them. 

The  grand  laws  of  meteorology,  which  Maury  so  admirably  reduced 
to  harmony  from  phenomena  often  of  the  most  fleeting  character  and 
complicated  by  local  anomalies,  have  by  experience  been  demon- 
strated in  detail  to  be  of  great  service  for  the  security  of  navigation. 

Some  of  these  points,  especially  those  relating  to  the  currents  and 
surface  temperatures  of  the  North  Atlantic,  we  will  proceed  to  inves- 
tigate in  this  paper. 

The  scientific  expeditions  so  wiselj'  directed  by  the  governments  of 
the  United  States,  England,  Germany,  and  France  for  the  physical 
examination  of  the  ocean,  in  connection  with  the  deep-sea  sound- 
ings for  the  trans- Atlantic  submarine  cables,  have  covered  the  sea  so 
thoroughly  with  a  net  of  observations  that  scarcely  any  important 
feature  has  escaped  their  investigations.  They  have  established  that 
no  part  of  the  ocean  is  at  rest,  but  that  the  entire  mass  of  the  ocean 
from  the  surface  to  the  profoundest  depths  is  constantly  in  motion 


NORTH    ATLANTIC    CURRENTS.  193 

to  re-establish  the  equilibrium  destroyed  by  the  action  of  tides,  the 
pressure  of  winds,  and  the  changes  of  temperature  and  density. 

The  waters  of  the  ocean  are  subjected  to  a  double  circulatory  move- 
ment, vertical  and  horizontal. 

The  vertical  motion  is  determined  by  the  study  of  the  submarine 
isotherms.  The  cold  polar  waters  sink  below  the  waters  of  temperate 
zones,  and  ascend  toward  the  surface  in  tropical  zones,  where  they 
cause  great  evaporation. 

The  horizontal  circulation  on  the  surface  was  known  to  ancient 
navigators  who  utilized  or  defied  it.  This  is  found  in  all  oceans 
more  or  less  permanent  or  intermittent  and  its  most  energetic 
actions  are  produced  near  the  coasts  by  the  tidal  action  and  at  sea 
by  the  effect  of  the  wind. 

The  action  of  the  wind  upon  the  surface  water  is  most  effective ; 
it  produces  the  waves  and  carries  the  molecules  of  water  to  leeward, 
and  often  in  a  cul  de  sac  raises  the  surface  many  meters  high,  and 
under  continuous  action  often  stops  the  tides. 

Especially  in  the  Atlantic  the  continuous  action  of  the  northeast 
and  southeast  trades  forces  the  inter-tropical  waters  westward,  where 
the  configuration  of  the  coast  at  the  mouth  of  the  Amazon  River 
deflects  the  waters  to  the  Windward  Islands,  through  the  numerous 
passages  between  these  islands  into  the  Caribbean  Sea.  The  barrier 
formed  by  the  large  islands  of  Puerto  Rico,  Haiti,  and  Cuba,  compels 
the  accumulating  waters  to  enter  the  Gulf  of  Mexico,  whose  surface 
level  is  thereby  raised,  and  then  finds  its  only  exit  between  Cuba  and 
Florida.  Thence  these  waters  meet  the  coral  banks  of  the  Bahamas 
and  form  an  enormous  river  with  a  rapid, current  which  follows  the 
coast  of  the  United  States  to  Cape  Hatteras,  where  it  is  known  as  the 
Gulf  Stream.  Thence  deflected  to  pass  south  of  Newfoundland  and 
the  Grand  Banks,  it  opens  out  like  a  fan  and  spreads  over  the  sur- 
face of  the  North  Atlantic,  with  a  loss  of  its  speed  and  much  of  its 
distinctive  character. 

The  name  of  Lieut.  Pillsbury  is  forever  associated  with  other  enter- 
prising scientists  of  the  United  States  Government  who  have  so  com- 
pletely investigated  this  remarkable  current. 

After  the  waters  of  the  Gulf  Stream  spread  out  over  the  sur- 
face the  axial  direction  follows  that  of  a  great  circle  which  passes 
north  of  the  Azores  and  reaches  the  coast  of  Portugal.  Here  two 
causes  operate  to  influence  the  current.  During  the  summer  the 
north  winds  in  prolongation  of  the  northeast  trades  along  the 
Portugal  coast  brush  these  waters  to  the  southward,  where  they  come 
under  the  influence  of  the  northeast  trades  and  the  region  of  the 
Equatorial  Current;  during  the  winter  the  southwest  winds  push 
these  waters  from  the  mid  North  Atlantic  to  the  northeast  to  the 
shores  of  Ireland  and  Norway. 
13 


194  CHICAGO    METEOROLOGICAL    CONGRESS. 

There  are  besides  the  Gulf  Stream  other  currents  which  are  recog- 
nized as  permanent  and  have  certain  general  features,  such  as  the 
Labrador  Current,  caused  by  the  melted  snow  and  ice  of  polar  regions, 
and  the  Counter  Equatorial  Current,  produced  by  the  southwest  winds 
of  the  coast  of  Africa. 

These  currents  have  been  found  by  observations  of  navigators  and 
from  the  drift  of  floating  objects,  such  as  ice,  wood,  bottles,  and  hulls 
of  vessels.  The  observations  conducted  for  the  Pilot  Charts,  published 
by  the  Hydrographic  Office  of  the  U.  S.  Navy,  at  Washington,  D.  C, 
have  been  of  great  importance.  These  show  the  precise  resultant  of 
the  complicated  causes  to  which  a  floating  vessel  is  subjected.  If 
the  hull  of  a  derelict  vessel,  immersed  6  to  8  meters  in  the  water 
without  exposing  to  the  wind  more  than  a  portion  of  its  dismantled 
hull,  should  for  several  days  in  a  month  drift  in  a  certain  direction 
it  is  evident  that  the  mass  of  water  in  which  it  floats  must  have 
moved  in  the  same  direction. 

There  are  other  surface  movements  of  the  sea  which  are  designated 
as  permanent  currents,  but  which  facts  show  are  subject  to  important 
and  unforeseen  variations.  An  examination  of  the  Pilot  Charts  will 
show  several  examples. 

We  beg  the  reader  carefully  to  examine  these  charts,  and  especially 
certain  supplements  which  have  been  published  by  the  Washington 
Hydrographic  Office,  viz  :  "  The  Drift  of  Bottle  Papers,"  July,  1891 ; 
"  The  Derelict  Schooner  White,"  February,  1889. 

We  will  proceed  to  investigate  the  following :  The  Norwegian  Cur- 
rent, the  Rennell  Current,  the  currents  of  the  coast  of  Portugal  and 
the  west  coast  of  Africa,  the  currents  of  the  Sargasso  Sea,  and  the 
temperatures  of  the  sea  from  Bordeaux  to  the  La  Plata  River,  from 
Bordeaux  to  New  York,  and  in  the  Bay  of  Biscay. 

THE    NORWEGIAN    CURRENT. 

In  summer  the  Atlantic,  north  of  the  Azores,  does  not  appear  to 
be  so  much  under  the  influence  of  the  Gulf  Stream,  and  yet  in  that 
season  the  stream  has  its  greatest  extension  toward  the  north,  a  fact 
which  is  demonstrated  by  the  tracks  of  the  derelicts  Twenty-one 
Friends,  in  July,  August,  and  September,  the  White,  in  June,  July, 
August,  and  September,  the  E.  Davis,  in  August  and  September,  and 
the  Hunt,  in  July. 

In  the  season  when  the  southwest  and  west  winds  prevail  the  waters 
are  pushed  northeast  and  east.  The  fact  is  shown  by  the  drift  of 
numerous  derelicts  published  on  the  Pilot  Charts,  and  of  the  drift  of 
bottle  papers  in  the  special  supplement  of  the  Pilot  Charts,  1891-'92. 
Nevertheless,  even  in  this  season,  the  condition  of  the  barometric 
pressure  on  the  Atlantic  prevents  the  westerly  winds  from  allowing 
these  waters  to  reach  the  shores  of  Europe.     The  surface  waters  do 


Plate  Vin. 


Currents  of  the  North  Atlantic  in  1892. 

Path?  of 'drifting  wrecks. 


Eauireux. 


20 


30 


20 


Temperature  of  water  in  the  Bay  of  Biscay. 


1 


Jjongfitades  West  of  Osreenrrich. 
70 9        __  3  y  <^ ^ 


Octoher 

JVoyem.be7 

MeceTttbef 


NORTH  ATLANTIC  CURRENTS.  195 

not  always  follow  their  usual  course,  as  is  shown  by  the  tracks  of  the 
derelicts  Countess  Dufferin,  Vestalinden,  and  Daphne,  which  drifted 
toward  the  south  and  south-southeast.  (See  Plate  viii.)  For  dur- 
ing these  months  anticyclones  covered  the  North  Atlantic,  and  rare 
depressions  traversed  the  European  coasts,  traveling  from  north- 
northwest  to  south-southeast. 

These  facts  appear  to  prove  to  us  that  the  wind  predominates  in 
giving  direction  to  the  surface  waters  of  this  part  of  the  Atlantic. 
Fine  weather  and  light  winds  prevailed  during  the  summer,  and  the 
drifting  derelicts  show  that  then  the  surface  waters  are  most  fre- 
quently transported  with  continuous  regularity.  During  the  season 
when  strong  winds  blow  from  the  south  and  west  the  waters  are 
forced  to  the  north  and  east,  but  whatever  may  be  the  cause,  those 
strong  west  winds  fail  to  make  the  derelicts  always  follow  the  im- 
pulse they  receive. 

Drifting  bottles  launched  northwest  of  the  Azores  by  the  yacht 
L'Hirondelle,  which  were  recovered  in  the  Azores  Islands,  clearly 
prove  that  this  current  has  not  the  degree  of  permanence  which  has 
been  ascribed  to  it  as  a  branch  of  the  Gulf  Stream. 

This  current  is  absolutely  dependent  upon  the  surface  winds  which 
in  summer  force  the  waters  of  the  mid-Atlantic  toward  the  European 
coasts  with  a  temperature  always  above  10°  C. 

CURRENTS   IN    THE    BAY    OF    BISCAY. 

The  so-called  Rennell  Current  is  represented  as  a  derivative  of  the 
Gulf  Stream  which  meets  the  coast  at  Cape  Finisterre  and  then 
divides  into  two  branches,  one  of  which  flows  south  along  the  coast 
of  Pprtugal,  the  other  enters  the  Bay  of  Biscay,  following  the  north 
coast  of  Spain,  thence  flows  north  and  northwest  along  the  French 
coast  and  is  lost  in  the  general  currents  of  the  channel. 

The  drifting  derelicts  are  again  quoted  to  present  facts  not  in 
accord  with  this  theory,  viz:  Tiventy-one  Friends,  in  1886;  Stormy 
Petrel,  in  1887 ;  Emilie  and  Petty,  in  1888 ;  Atlas,  Carrier  Dove,  and 
Herman,  in  1890;  schooners  Ryerson  and  Helios,  in  1891.  (See  Plate 
VIII.)  Besides,  in  the  drift  of  bottle  papers,  Nos.  12,  17,  29.  and  30 
have  also  followed  anomalous  directions.     (See  Plate  ix.) 

The  Prince  of  Monaco,  after  his  admirable  experiments  in  the 
yacht  UHirondeUe,  concludes  that  the  currents  in  the  Bay  of  Biscay 
are  contrary  to  the  Rennell  Current.  He  estimates  that  the  waters 
from  the  Gulf  Stream  divide  at  Ushant;  one  branch  goes  up  the 
channel  and  the  other  enters  the  Bay  of  Biscay,  flowing  southeast, 
then  south  along  the  coast  of  France,  and  finds  outlet  westward  along 
the  north  coast  of  Spain.  If  these  two  theories  are  correct,  we  have 
thought  that  there  might  be  a  point  on  the  French  coast  in  the  vi- 
cinity of  Arcachon  where  currents  would  be  found  regularly  setting 


196  CHICAGO    METEOROLOGICAL   CONGRESS. 

north  and  south.  This  must  appear  logical  on  account  of  the  uniform 
regularity  of  the  coast  line  there,  so  that  this  important  sheet  of  water 
is  not  influenced  by  eddies  such  as  would  be  found  upon  an  indented 
shore. 

There  is,  fortunately,  at  Arcachon  a  fishing  industry  having  five 
steamers,  under  the  direction  of  Mr.  H.  Johnson,  who  readily  con- 
sented to  assist  our  investigations  and  ordered  bottle  papers  to  be 
launched  for  this  purpose.  The  captains  of  these  vessels  made  the 
following  reports,  which  have  been  forwarded  to  the  Hydrographic 
Office  at  Washington,  D.  C. 

Extract  from  the  report  of  Capt.  Pateau : 

The  currents  are  not  regular.  They  are  caused  by  the  wind;  with  north  winds  the 
currents  set  south,  and  with  south  winds  they  set  north.  At  times  there  is  no  current 
with  the  wind  east  offshore.     In  winter  the  currents  are  stronger  than  in  summer. 

Extract  from  the  report  of  Capt.  Durand : 

I  have  always  noticed  that  when  the  wind  is  south  or  southwest  the  currents  set  north 
along  the  coast  of  France,  but  with  the  wind  northeast  or  northwest  they  set  south  to- 
ward the  bottom  of  the  bay,  and  thence  flow  west  along  the  coast  of  Spain,  with  a 
velocity  proportional  to  the  strength  of  the  wind  and  its  continuance. 

Extract  from  the  report  of  M.  Silhouette,  of  Biarritz : 

Formerly  many  small  trading  vessels  frequented  Bayonne  and  were  often  lost.  The 
vessels  were  carried  perpendicularly  to  shore,  head  on.  Subsequently  their  sterns  were 
carried  south  by  the  current  from  the  north. 

All  these  reports  agree  that  the  currents  in  the  Bay  of  Biscay  are 
absolutely  dependent  upon  the  prevailing  winds. 

In  order  to  confirm  these  reports  we  have,  during  June  and  July  of 
this  year,  thrown  overboard  a  number  of  bottles,  three-fourths  full  of 
water,  attached  to  floats  by  a  line  two  fathoms  long.  The  length  of 
the  line  being  such  that  the  bottles  might  be  readily  recovered  on  the 
coast  at  low  tide.  These  bottles  were  thrown  overboard  12  to  30  miles 
from  the  coast  in  depths  of  40  to  60  fathoms. 

The  results  of  these  experiments  were  collected  and  sent  to  the 
Hydrographic  Office  at  Washington,  D.  C,  which  office  is  hereby  re- 
quested to  communicate  them  to  the  Congress.  The  experiments  were 
commenced  on  May  25  and  continued  at  the  rate  of  three  or  four 
every  week.  The  last  one,  recovered  on  July  3,  had  been  thrown 
overboard  on  June  21,  by  the  steamer  Oceanique.  Out  of  the  eigh- 
teen or  nineteen  bottles  thrown  overboard,  thirteen  were  recovered — 
a  large  proportion.     (See  table  on  page  198  and  Plate  ix.) 

The  currents  observed  on  board  the  vessels  where  the  bottles  were 
thrown  overboard  were  weak  and  the  general  set  was  south-southwest. 
The  bottles  were  adrift  in  the  water  for  an  average  period  of  fourteen 
days,  and  the  resultant  direction  of  their  drift  was  to  the  south-south- 
east. Not  one  bottle  was  found  north  of  the  place  whence  it  was  set 
adrift.     This  is  contrary  to  the  theory  of  the  Rennell  Current. 


Drifting  bottles,  June,  1 893. 


Plate  IX. 


Haxdreux. 


NORTH    ATLANTIC    CURRENTS.  197 

North  of  the  region  observed  the  prevailing  wind  during  the  period 
from  May  25  to  June  22  was  toward  the  southwest,  while  south  of 
that  region,  near  Biarritz,  the  mean  direction  was  toward  the  east- 
southeast.  The  resultant  direction  of  the  drift  of  the  bottles  was 
south-southeast,  which  direction  is  the  mean  resultant  of  a  drift  first 
to  the  southwest  and  then  east-southeast.  The  velocity  of  the  drift, 
derived  by  dividing  the  distance  drifted  by  the  number  of  days  afloat, 
was  for  twenty-four  hours  a  maximum  of  4.2  miles,  a  minimum  of 
1.4,  and  a  mean  of  2.5. 

Upon  examining  the  sketch  it  will  be  seen  that  the  bottles  may  be 
classed  in  two  groups — A,  B,  H,  L,  and  N,  which  drifted  east-south- 
east, and  C,  D,  E,  F,  G,  I,  K,  and  M,  which  drifted  toward  the  south 
and  south-southeast. 

There  are  two  charts  of  the  currents  of  the  Bay  of  Biscay,  one  by 
G.  Simart,  Lieutenant,  French  Navy,  published  in  1889,  and  one  by 
the  Prince  of  Monaco,  1892.  In  the  Simart  charts  the  currents  of 
the  Bay  of  Biscay  are  laid  down  as  setting  south  at  the  rate  of  4  to  5 
miles  in  twenty-four  hours.  In  the  chart  of  the  Prince  of  Monaco, 
the  currents  are  laid  down  as  setting  east  at  the  rate  of  6.6  miles 
for  twenty-four  hours.  The  two  directions  are  at  right  angles  to  each 
other.  Our  experiments  do  not  reconcile  the  difference.  The  tracks 
of  shortest  periods  are  those  of  the  Prince  of  Monaco,  the  longer  tracks 
are  those  on  the  chart  of  Lieut.  Simart.  But  there  is  one  fact  to  be 
remarked  that  on  the  chart  of  the  Prince  of  Monaco  the  shortest  drift 
tracks,  considered  as  best  indicating  the  direction  and  set,  were  made 
during  September,  October,  November,  and  December,  1886.  In  this 
year  the  autumn  was  characterized  by  excessive  rains  in  the  Bay  of 
Biscay.  The  records  of  the  observatory  at  Bordeaux  show  a  rainfall 
for  September  of  102  mm.  and  October,  205  mm.  This  is  double  the 
mean  rainfall.  This  excessive  rainfall  is  certain  proof  of  the  frequency 
and  violence  of  the  west  winds  in  the  fall  of  1886.  It  is  probable, 
therefore,  that  the  effects  of  the  wind  transporting  the  water  caused 
the  current  to  set  east  at  the  rate  of  6.6  miles  per  twenty-four  hours, 
a  rate  three  times  as  fast  as  was  experienced  in  our  experiments  during 
June  of  this  year. 

Our  results  were  obtained  during  a  period  in  which  fine  weather 
prevailed,  and  they  show  that  floating  bodies  drift  to  the  east  and 
south  of  the  point  of  departure  during  the  month  of  June,  and  that 
they  are  pushed  with  a  sl(5w  and  irregular  velocity.  A  set  of  2.5 
miles  in  twenty-four  hours  can  scarcely  be  called  a  current. 

These  facts  demonstrate  that  the  Rennell  Current  has  neither  the 
permanence  nor  the  velocity  with  which  it  is  credited,  and  that  at 
least  during  the  summer,  along  the  French  coast,  the  current  sets 
more  frequently  south  than  north.     It  is  also  seen  that  it  sets  toward^ 
the  beach,  a  feature  most  dangerous  to  vessels.     This  explains  the 


198 


CHICAGO    METEOROLOGICAL    CONGRESS. 


dangerous  character  which  has  always  been  accredited  to  the  Bay  of 
Biscay.  No  sailing  vessel  can  beat  off  the  coast  while  the  winds  and 
currents  both  set  her  on.  These  facts  show  that  the  wind  is  the 
preponderating  factor  in  causing  the  currents  whose  direction  and  set 
are  often  modified  by  the  configuration  of  the  coast.  They  prove  also 
that  near  the  coast  there  is  a  surface  movement  which  is  dangerous 
to  navigation  and  should  be  studied  carefully. 

Table  of  drifting  bottles  near  Arcachon. 


Thrown  into  the  sea. 


Recovered. 


Drift. 


Designating 
letter. 


A 

B 

C 

D 

E 

F 

G 

H 

1  . 

K 

L 

M 

N 


Lati- 
tude. 


44  12 
44  II 
44  12 
44  40 
44  4° 
44  3° 
44  24 
44  07 
44  36 
44  30 
44  13 

44  30 

45  32 


Distance 

off- 

sliore. 


Miles. 


34 


Current. 


Lati- 
tude. 


SW. 

SSE. 

8W. 

NW. 

NW. 

NNE. 

NNE. 

SSW. 

NNE. 

SW. 

SW. 

SW. 

SW. 


Longi- 
tude, 

Green- 
wich. 


44  08 
44  07 

43  44 

44  00 

43  44 
43  43 

43  57 

44  02 
43  26  i 
43  56 
43  55  I 
43  22  I 

45  20 


I  20 
I  20 
I  24 
I  21 
I  24 
I  24 
I  28 
I  21 
I  33 
I  28 
I  28 
I  54 
I  12 


Distance. 


Direction. 


MUes. 


S.  70  E. 

S.  78  E. 

S.  18  E. 

S.  10  E. 

S.  5  E. 

8.  15  E. 

S.  20  E. 

S.  70  E. 

S.  3  E. 

S.  25  E. 

8.  34  E. 

S.  4W. 

S.  70  E. 


Days. 


Rate  of 
drift. 


MUes. 


2.9 
2.8 
1-7 
1.4 
4.2 
2-5 
2.4 
3-8 


CURRENTS    OF    PORTUGAL    AND    WEST    COAST    OF    AFRICA. 

For  this  the  observations  of  the  steamers  of  the  Messageries  Mari- 
times,  taken  from  time  to  time  for  six  years  with  about  four  each 
month,  are  considered  in  detail.  These  steamers  ply  along  the  coast 
of  Portugal  and  Africa  as  far  as  the  Cape  Verde  Islands.  The  cur- 
rents have  not  the  permanence  to  which  they  are  credited,  but  in 
each  season  there  are  certain  features. 

Winter. — Along  the  coast  of  Portugal  the  current  sets  north  and 
north-northwest ;  from  Madeira  to  the  Canary  Islands  the  current 
sets  north-northeast,  and  from  the  Canary  Islands  to  Dakar  the  cur- 
rent sets  west-southwest.  The  Counter  Equatorial  Current  sets 
southeast. 

Summer. — Along  the  coast  of  Portugal  the  current  sets  south  to 
south-southeast.  From  Madeira  tQ  the  Canaries  the  current  sets 
south-southwest.  From  the  Canaries  to  Dakar  the  current  sets  south- 
southwest.  The  Counter  Equatorial  Current  sets  east.  A  velocity  of 
about  one  mile  per  hour  has  been  foun'd  between  the  Canaries  and 
Dakar  and  between  the  equator  and  Pernambuco. 

The  difference  in  direction  in  summer  and  winter  corresponds  with 
the  changes  in  the  direction  of  the  prevailing  winds  in  these  regions 
in  these  seasons.  During  the  winter  southwest  winds  are  frequent  be- 
tween Madeira  and  Cape  Finisterre,  and  they  force  the  water  to  lee- 
ward to  the  north.      In  summer  northerly  winds  prevail  and  force 


NORTH    ATLANTIC    CURRENTS.  199 

the  water  south.  Near  Dakar,  in  the  period  of  the  southwest  mon- 
soons of  the  coast  of  Africa,  the  Counter  Equatorial  Current  carries 
warm  water  ashore  near  the  Arquin  Bank,  Cape  Blanco. 

It  is  to  be  noticed  that  in  the  trade-wind  regions  the  westerly  com- 
ponent of  the  current  is  always  greater  than  that  of  the  wind. 

THE    SARGASSO    SEA. 

Southwest  of  the  Azores  the  waters  of  the  Atlantic  form  a  large 
whirlpool  analogous  and  corresponding  to  the  general  circulation  of 
the  surface  winds.  The  movement  is  demonstrated  by  the  drifts  of  the 
derelicts  Telemach,  Drury,  Wyer  G.  Sargent,  and  Fannie  E.  Wolston. 
The  diameter  of  the  curves  of  these  tracks  is  from  350  to  400  miles. 

These  drifts  are  evidently  the  resultant  effects  of  the  surface  winds. 
For  in  this  sea  the  drifts  to  the  westward  took  place  from  July  to 
November  during  the  period  when  the  trades  extended  farthest  north, 
and  to  the  north  and  east  during  the  winter  months,  when  the  jsre- 
dominant  winds  in  that  region  were  south  and  west.  The  agreement 
in  the  directions  of  the  winds  and  the  oceanic  surface  drift  is  there- 
fore complete. 

CURRENTS    BETWEEN    BERMUDA    AND    THE    WEST    INDIES. 

All  charts  show  in  this  region  a  prolongation  of  the  equatorial 
drift  toward  the  north,  and  a  large  mass  of  water  passing  north  of 
the  West  Indies  and  joining  the  right  side  of  the  Gulf  Stream. 

Notwithstanding  this  the  Pilot  Charts  show  that  the  derelicts  Vin- 
cenzo  Perrota,  Ida  Francis,  Mary  Douglass,  and  Rita  were  for  several 
months  in  that  vicinity  without  being  drifted  by  that  current.  In 
the  chart,  "Drift  of  Bottle  Papers"  (No.  ix),  bottles  Nos.  5,  88,  106, 
and  129,  also  show  that  if  such  a  current  exists  at  times  it  has  not 
the  permanence  attributed  to  it  by  the  charts.  It  can  be  said  that 
the  drifts  of  the  floats  are  directly  contrary  to  the  current  indicated 
on  the  charts. 

From  all  these  observations  we  may  conclude  that  the  wind  is  the 
great  cause  for  most  of  the  surface  movement  of  the  sea.  Its  action 
causes  the  deviations  from  the  displacement  due  to  the  tides  and 
glacial  discharges. 

TEMPERATURE  OF  THE  SEA  BETWEEN  BORDEAUX  AND  LA  PLATA. 

The  study  of  the  submarine  temperatures  has  revealed  the  laws  of 
the  vertical  circulation  of  waters.  In  examining  the  submarine 
isotherms  along  a  meridian  one  is  at  once  struck  by  the  marked  in- 
clination of  these  isotherms  near  shoals,  the  horizontality  of  the  lines 
in  temperate  zones,  and  their  rise  toward  the  surface  in  warmer 
regions. 

It  is  difficult  to  explain  why  the  isotherm  of  7°  to  10°  C,  after 
descending  to  a  depth  of  1,500  to  2,000  meters  near  the  Canaries, 


200 


CHICAGO    METEOROLOGICAL   CONGRESS. 


should  rise  to  nearly  200  or  300  meters  below  the  surface,  contrary  to 
all  the  laws  of  gravity  and  to  the  movement  of  the  waters  by  the 
surface  winds.  It  must  surely  be  due  to  the  tropical  evaporation  and 
the  necessity  of  replacing  the  equatorial  waters  that  the  vertical 
movement  acts  like  a  vast  pump.  If  there  is  one  place  where  this 
movement  is  specially  emphasized,  we  believe  such  a  place  exists  in 
the  vicinity  of  Cape  Blanco,  Africa,  near  Arquin  Bank. 

The  observations  of  temperature  of  the  mail  steamers  of  the  Mes- 
sageries  Maritimes  on  their  voyages  between  Bordeaux  and  the  La 
Plata  (see  table  below)  show  that  the  temperature  between  Lisbon 
and  the  Canaries  increases  regularly  by  4°  to  6°  C,  and  that  this 
increase  augments  most  rapidly  in  November  and  least  in  March. 

Temperature  of  the  sea  between  Bordeaux  and  the  La  Plata. 


Longitude 

h 

£• 

% 

% 

u 

^ 

S 

west  of 

Latitude. 

C3 

a 

A 

<n 

.2 

s 

s 

Greenwich. 

3 

»4 

0 

'^ 

>• 

3> 

>> 

s 
tp 

0. 

2 

>• 

§ 

05 

<s> 

03 

P. 

eS 

s 

"a 

3 

4> 

0 

0 

4> 

"^ 

i. 

s 

< 

s 

l-» 

"-5 

< 

m 

0 

Zi 

Q 

0 

, 

0 

• 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

4 

00 

N. 

45 

00 

12.0 

II. 0 

12.0 

12.0 

14-5 

16.5 

17.0 

19.0 

19.0 

17.0 

14-5 

13-0 

9 

30 

N. 

42 

30 

13.0 

12-3 

12.5 

12.2 

13-4 

15-6 

16.4 

17.9 

17-4 

14.0 

13-4 

13-0 

9 

30 

N. 

40 

00 

14-8 

14.6 

13-7 

14. 1 

14.6 

16.5 

16.9 

18. 1 

18.6 

17-5 

'§•7 

14.0 

10 

00 

N. 

37 

30 

16.0 

15-3 

15.0 

15.0 

15-5 

18.0 

17.6 

20.2 

20.0 

20.2 

18.3 

16.0 

II 

00 

N. 

35 

00 

18.0 

16.3 

16.0 

16.0 

17-5 

18.7 

19.8 

21.7 

21.2 

21-3 

19-5 

18.0 

12 

30 

N. 

32 

30 

18.0 

17.0 

17-5 

17.0 

18.0 

19-5 

20.4 

22.1 

21.7 

21.0 

20.6 

18.6 

14 

00 

N. 

30 

00 

18.5 

17-5 

17.7 

17.6 

19.0 

20.0 

20.7 

22.2 

22.7 

22.0 

21. 1 

19.4 

15 

00 

N. 

27 

30 

18.6 

17-5 

18.5 

18.5 

19.8 

20.5 

21.0 

22.8 

24.0 

22.5 

22.1 

20.0 

i6 

30 

N. 

25 

00 

18.5 

18.0 

19.0 

19.6 

19.8 

20. 1 

20.6 

22.2 

21-3 

22.0 

22.6 

20.0 

17 

30 

N. 

22 

30 

17.9 

17-5 

18.0 

19.0 

19.2 

18.9 

.19-9 

21-5 

20.4 

21.3 

23.1 

20.0 

l8 

00 

N. 

20 

00 

17-3 

18.5 

20.0 

17.4 

17-7 

17-5 

22.4 

24-5 

25.0 

20.8 

21.0 

22.0 

i8 

00 

N. 

17 

30 

19.8 

19.0 

21-3 

19.2 

20.4 

22.2 

25.8 

25-6 

27.0 

26.8 

22.7 

24.4 

l8 

00 

N. 

15 

00 

22.6 

22. 1 

20.5 

20.5 

23.2 

25-4 

27.0 

27.4 

27.2 

29-5 

26.4 

25-1 

19 

00 

N. 

12 

30 

25-3 

23-7 

23.0 

24.0 

25- 1 

27.8 

26.3 

27.1 

28.0 

28.2 

26.9 

25-8 

21 

00 

N. 

10 

00 

26.1 

25-0 

25.0 

25-4 

26.1 

27.8 

26.4 

27.0 

27.0 

28.0 

27-3 

27.1 

23 

00 

N. 

7 

30 

26.9 

27.0 

26.0 

27-5 

27.1 

27-3 

26.3 

27.4 

27.0 

26.6 

27.0 

27.4 

24 

30 

N. 

5 

00 

26.6 

27.0 

27.0 

28.5 

27-5 

27.8 

26.0 

27.0 

26.6 

27.4 

26.7 

27-5 

26 

30 

N. 

2 

30 

26.4 

27.0 

27.8 

26.7 

28.0 

28.5 

26.0 

25.0 

25-4 

26.7 

26.2 

26.7 

28 

00 

0 

00 

25-9 

26.7 

27.0 

26.1 

27.7 

28.0 

25-4 

25.0 

25-4 

25-9 

26.0 

26.1 

29 

30 

S. 

2 

30 

26.0 

26.7 

27-5 

27-3 

27.1 

27.0 

25-4 

25.0 

25-5 

25-5 

25-9 

26.1 

31 

30 

s. 

5 

00 

26.4 

26.5 

27.9 

27.4 

27.8 

26.5 

25-7 

25-9 

25-6 

25-2 

25-7 

26.4 

33 

00 

8. 

7 

30 

26.7 

27.0 

27.9 

27.0 

27-5 

26.0 

25-8 

25-7 

25-8 

25-5 

25-7 

26.8 

34 

30 

s. 

10 

00 

26.9 

27.0 

27.6 

27.0 

27.1 

25-8 

25-3 

25-3 

25-3 

25-4 

25-5 

26.7 

36 

00 

s. 

12 

30 

25.7 

27.0 

27-3 

27.1 

26.3 

25-8 

24.7 

24.9 

24-5 

25-4 

25-5 

26.3 

37 

00 

s. 

15 

00 

26.4 

26.6 

27-3 

26.7 

25-7 

25-5 

24-5 

24-5 

24.0 

23-5 

25-4 

26.3 

38 

00 

s. 

17 

30 

25-6 

25.5 

27.1 

26.6 

25-7 

25.0 

24.2 

24.2 

24-1 

23-5 

24. 8 

25-9 

39 

00 

s. 

20 

00 

25-6 

26.5 

26.5 

26.2 

25-3 

24-5 

23.1 

23-5 

23-3 

23-4 

21.9 

25-4 

40 

00 

s. 

22 

30 

23-3 

21.0 

24-5 

23.0 

21.8 

20.0 

20.0 

20.5 

20.2 

19-3 

20.4 

21.8 

45 

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From  the  Canaries  to  the  Arquin  Bank  the  temperature  falls  from 
2°  to  2^°  C.  from  April  to  November.  The  fall  is  less  marked  but  is 
found  also  during  the  winter  months.  The  center  of  the  thermal 
depression  oscillates  between  N.  20°  and  N.  22°,  it  runs  near  the  coast 
on  the  level  of  the  peninsula  of  Cape  Verde,  and  it  is  deflected  at  the 
time  the  currents  change  direction. 

From  the  Arquin  Bank  to  Dakar  there  is  a  sudden  thermal  rise  of 
8°  to  9°  C.  in  September  and  October;  the  rise  is  less  in  March  and 
April.     The  sharp  bend  in  the  isotherms  has  also  been  established  by 


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NORTH    ATLANTIC    CURRENTS. 


201 


the  exploring  expedition  of  the  Talisiiian.  On  this  vessel  it  was  ob- 
served that  the  density  of  the  surface  waters  was  only  1,024.8  or  3.0 
less  than  that  of  neighboring  waters,  and  also  that  this  diminution 
in  the  saltness  exists  in  deep  layers  when  the  temperature  is  as  low 
as  7°  C. 

This  low  density  accompanied  by  low  temperature  in  this  warm 
region  proves  decidedly  the  polar  source  of  these  waters  and  their  rise 
to  the  surface.  The  color  of  this  water  is  also  different,  being  green 
while  the  neighboring  trade-wind  water  is  blue.  The  depths  reach 
2,200  meters. 

The  observations  on  the  mail  steamers  show  another  point  of 
thermal  depression  and  rise  to  the  surface.  This  is  near  Cape  Frio. 
In  the  warm  season  when  the  rainfall  is  most  marked  the  thermal 
depression  is  about  3°  or  4°  C. 

FROM  BORDEAUX  TO  NEW  YORK. 

The  Bordelaise  mail  steamers  plying  between  Bordeaux  and  New 
York  have  willingly  given  me  the  results  of  their  observations  for 
several  years,  1882  to  1887.  The  route  of  these  steamers  crosses  the 
fortieth  meridian  in  N.  47°  30'  and  passes  the  southern  extremity  of 
the  Banks  of  Newfoundland. 

In  the  curve  of  these  isotherms  one  is  at  once  struck  by  their  ir- 
regularities between  the  fortieth  meridian  and  New  York,  and  by 
their  absolute  uniformity  between  that  and  the  mouth  of  the  Gironde. 

Temperature  of  the  sea  from  Bordeaux  to  New  York. 


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Therefore,  these  thermal  differences  near  the  American  coast  prove 
the  sources  of  the  waters  to  be  different,  while  the  main  currents  that 
reach  the  European  shores  are  more  stationary  and  are  pushed  and 
mixed  by  the  winds. 


202  CHICAGO    METEOROLOGICAL   CONGRESS. 

BAY    OF    BISCAY. 

In  a  region  so  contracted  there  can  not  be  great  thermal  diflferences. 
Such  small  differences  as  exist  are  evidences  of  the  movement  of  the 
waters  in  that  great  bay.  We  have  the  observations  of  the  mail 
steamers,  from  time  to  time,  for  a  distance  of  about  50  miles  from 
the  mouth  of  the  Gironde  to  Cape  Ortegal.  A  study  of  the  lines  of 
isotherms,  month  by  month,  shows  that  in  the  months  of  June,  July, 
and  August  there  is,  along  the  fourth  meridian  west  of  Greenwich,  a 
mass  of  water  about  100  miles  wide,  whose  temperature  is  about  2° 
or  3°  C.  higher  than  that  of  the  French  coast  waters,  and  that  from 
this  point  to  Cape  Ortegal  the  temperature  gradually  falls  in  the 
summer  months  until  it  is  2°  C.  lower  than  that  of  the  coast  waters. 
(See  tables  and  plate.) 

This  state  of  things  indicates  that  the  Rennell  Current  does  not 
exist  during  the  summer  months  as  stated  on  the  chart.  To  supply 
this  mass  of  warm  water  along  the  fourth  meridian,  one  can  only 
find  an  oceanic  source,  and  to  furnish  the  cold  waters  of  Cape  Orte- 
gal it  can  only  be  ascribed  to  the  melting  ice  of  the  mountains  on  the 
north  coast  of  Spain.  These  flow  along  the  coast  from  east  to  west 
until  they  meet  the  oceanic  waters  at  Cape  Finisterre. 

During  the  months  of  November  and  December  the  temperature  of 
the  water  is  higher  at  Cape  Ortegal  than  near  the  mouth  of  the 
Gironde.  These  are  the  months  of  the  west  winds  on  the  coast  of 
Portugal.  These  winds  at  the  same  time  blow  from  the  northwest  on 
the  French  coast  and  suffice  to  explain  the  thermal  difference. 

These  observations  of  the  temperature  of  the  sea  clearly  show  that 
the  waters  of  the  Bay  of  Biscay  are  differently  affected  in  summer 
and  winter.  During  the  fine  season,  in  a  period  of  comparative  calms, 
in  the  Bay  the  surface  Avaters  are  rather  stationary,  and  are  heated 
more  than  the  coast  waters  by  the  influence  of  the  winds  and  tides. 

The  experiments  with  drifting  bottles  show  that  in  the  summer 
months  that  the  coast  waters  are  subject  to  a  slight  movement.  The 
Rennell  Current  has  not  the  permanence  nor  the  dimensions  with 
which  it  is  credited.  In  the  Bay  of  Biscay  there  are  variable  coast 
currents  depending  upon  the  force  and  direction  of  the  winds. 

The  conclusion  that  may  be  drawn  from  this  study  is  that  all  the 
ocean  currents  marked  on  the  charts  are  more  or  less  deflected  by  the 
winds,  and  that  even  the  most  constant  currents  such  as  the  Equa- 
torial Currents,  the  Gulf  Stream,  and  the  Labrador  Current  are  sub- 
ject to  their  influence.  The  branch  currents  which  wash  the  shores 
of  western  Europe  and  Africa  are  even  more  sensitive  to  the  winds. 

The  currents  on  charts  should  be  accepted  as  the  general  condition, 
but  it  must  always  be  Ijorne  in  mind  that  the  wind  dominates  and  is 
the  grand  factor  in  surface  movements. 


NORTH  ATLANTIC  CURRENTS, 


203 


The  changes  in  the  temperature  and  saltness  of  the  sea  are  also  a 
principal  cause  of  the  movements  of  the  waters,  especially  at  certain 
depth.  The  effects  of  melting  ice  and  fluvial  discharges  may  be  seen 
when  the  weather  is  calm,  but  numerous  facts  have  shown  that  under 
these  conditions  the  intermingling  of  the  waters  is  slow  without  the 
agency  of  the  wind. 

It  must  also  be  admitted  that  there  has  been  too  much  generalizing 
with  conditions  which  in  reality  are  only  more  or  less  frequent  in 
certain  seasons  and  not  permanent.  In  making  averages  of  observa- 
tions one  may  get  impressions  which  are  not  correct.  Thus,  in  charts 
of  mean  barometer  pressure  and  in  isotherms  in  inter-tropical  re- 
gions there  is  a  fact  which  approaches  the  truth,  since  in  these  regions 
the  extreme  variations  are  only  a  few  millimeters,  but  north  of  N. 
40°  what  signification  can  be  given  to  a  barometer  normal  when  it  is 
known  that  in  a  few  hours  there  may  be  changes  of  75  mm.,  and  that 
during  an  anticyclone  the  barometer  remains  at  785  for  a  week  in  a 
region  where  the  normal  is  in  fact  750  mm.  The  same  in  regard  to 
the  isotherms.  The  normal  mean  applies  very  well  to  inter-tropical 
regions  and  in  the  Atlantic  east  of  the  fortieth  meridian,  but  in  the 
neighborhood  of  the  Banks  of  Newfoundland  what  will  represent  the 
conditions  normally  when  the  ice  fields  and  icebergs  appear  and  cover 
one-fourth  of  the  Atlantic  and  then  for  another  season  fail  to  appear 
at  all. 

What  more  exact  information  can  be  obtained  than  is  given  on  the 
Pilot  Charts?  There  we  see  the  tracks  of  depressions,  the  frequency 
of  storms,  the  direction  of  currents,  the  direction  of  winds  and  per- 
centage of  calms  which  prevail  in  the  Atlantic  for  the  current  month. 
If  it  were  possible  to  add  to  the  text  of  the  Pilot  Charts  the  disposi- 
tion of  the  anticyclones  and  their  interdependence  in  regard  to  the 
high  pressure  on  the  Sargasso  Sea,  one  would  see  at  a  glance  of  the 
eye  the  actual  state  of  affairs  from  the  barometric  indication. 

Temperature  of  the  water  in  the  Bay  of  Biscay  from  the  mouth  of  the  Gironde  to  Cape 
Finisterre  {degrees  Centigrade). 


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19-5 

18.5 

17.5 

16.5 

14.  u 

8-5 

Cape  Ortegal 

10.. 

14-5 

13.0 

12.0 

12.0 

13-5 

17.0 

18.0 

19.0 

18.5 

i8-o 

17-5 

15-5 

7-5 

Do. 

II.. 

14.0 

13.0 

12.0 

12-5 

13.0 

15.0 

17.0 

18.0 

19.0 

18.0 

17.0 

15.0 

7-5 

C.  Finisten-e 

12.. 

13-0 

12.0 

12.0 

13.0 

14.0 

17.0 

19.0 

19-5 

18.0 

17.0 

16.0 

14.0 

7-5 

It  would  also  be  valuable  if  a  little  subchart  would  show  the  tem- 


204  CHICAGO    METEOROLOGICAL    CONGRESS. 

peratures  of  the  waters  in  the  neighborhood  of  the  Grand  Banks  as 
far  as  the  northern  limit  of  the  Gulf  Stream. 

Finally,  since  this  paper  is  addressed  to  the  Meteorological  Con- 
gress, they  should  formulate  this  resolution  : 

That  the  methods  of  giving  information  so  accurately  edited  in  the  Pilot  Chart 
should  be  adopted  by  all  the  maritime  nations  of  Europe;  that  their  methods  of  col- 
lecting information  be  adopted  and  the  charts  distributed  with  the  same  generosity;  that 
the  deposit  of  reports  from  log  books  be  made  obligatory,  and  that  the  captains  be  in- 
demnified by  frequent  publications. 

We  think  that  by  adopting  this  resolution  the  Congress  will  do  a 
useful  work,  and  in  a  great  degree  increase  the  security  of  life  and 
property  on  the  sea. 


9.— STORMS  IN  THE  SOUTH  ATLANTIC. 

Capt.    A.    P.    PlNHEIRO. 

Honored  with  the  confidence  placed  in  me  by  the  General  Com- 
mittee of  the  Congress  of  Meteorology  to  submit  a  report  on  the 
storms  of  the  South  Atlantic,  I  have  sought  to  comply  with  this 
courteous  invitation  with  the  means  which  I  had  at  my  disposal,  by 
touching  upon  the  few  data  as  yet  known  in  the  southern  seas  and 
taking  a  general  view  of  the  observations  to  the  present  time. 

I,  therefore,  divide  this  work  into  two  parts  :  ( 1 )  My  own  observa- 
tions from  1874  to  1893,  as  to  the  present  state  of  this  information 
and  as  to  what  should  be  done  for  its  progress  and  good  practical 
result.  (2)  Historical  observations  as  to  the  South  Atlantic  storms 
from  1789  to  1865,  covering  a  period  of  about  seventy-five  years.^ 

(1)  Personal  observations. — Since  1874  I  have  always  followed  with 
interest  the  South  Atlantic  storms,  and  I  observe  that  the  storms 
follow  a  general  direction  from  west  to  east  and  seek  to  throw  them- 
selves into  the  South  Atlantic  Ocean  from  the  Pacific,  or  over  the 
Brazilian  territory. 

I,  therefore,  bring  before  the  Congress  the  fact  that  I  am  endeavor- 
ing once  more,  by  utilizing  the  recent  reorganization  of  the  Meteoro- 
logical Service  of  Brazil,  brought  about  by  Admiral  Custodio  de  Mello, 
late  Minister  of  the  Navy,  to  realize  my  old  scheme  of  connecting 
by  telegraph  the  service  of  exchange  of  observations  between  Chile, 
Argentine  Republic,  and  Uraguay,  in  order  to  follow  with  more  pre- 
cision the  route  of  the  storms  in  the  South  Atlantic,  and  later  on  I 
shall  seek  to  connect  the  whole  service  of  South  America  and  to  place 
it  in  daily  correspondence  with  the  United  States  of  North  America, 

^  The  historical  part  of  Capt.  Pinheiro's  paper  comprises  the  interesting  description 
of  storms  in  the  South  Atlantic,  read  before  the  Soei6t^  Mtt^rologique  de  France  in 
1866,  by  M.  Martin  de  Moussi,  and  printed  in  the  Annuaire  of  the  society,  Vol.  xiv. 
1866.    pp.  15-22;  owing  to  limited  space  it  is  necessary  to  omit  it  here. — Editor. 


STORMS    IN    THE    SOUTH    ATLANTIC.  206 

When  news  reaches  me  by  telegraph  at  Rio  de  Janeiro  of  the  fall 
of  the  barometer  at  Valparaiso  or  Cordova,  I  know  from  past  expe- 
rience that  after  an  interval  of  from  three  and  a  half  to  six  days, 
according  to  the  velocity  of  the  wind,  bad  weather  may  be  expected 
on  the  eastern  coast  of  South  America,  as  storms  follow  the  general 
direction  from  west  to  east,  spread  themselves  over  the  interior  of 
Brazil,  and  become  spent  in  the  central  states  of  Sao  Paulo  and 
Minas  Geraes,  or  extend  along  the  seacoast  as  far  as  the  north  of  the 
State  of  Espirito  Santo. 

The  winds  of  the  South  Atlantic,  between  S.  23°  and  S.  56°,  pro- 
ceed generally  from  west,  southwest,  and  southeast;  but  north  of 
about  S.  18°,  they  blow  more  constantly  from  northeast  to  east, 
following  the  configuration  of  the  coast  to  the  mouth  of  the  Amazonas. 
Unfortunately  the  observations  made  in  the  basin  of  the  river  are 
few.  On  the  principal  river  east  winds  predominate  during  the 
greater  part  of  the  year,  notably  in  the  dry  season  from  November 
until  May,  when  they  are  rather  strong.  But  in  connection  with  the 
pamperos  of  the  months  of  June  and  July,  that  is  in  the  winter,  they 
are  still  stronger. 

Upon  a  superficial  examination  of  the  world  we  have  in  the 
northern  hemisphere,  as  well  as  in  the  southern,  movements  of  the 
air  from  the  west  toward  the  east.  In  storms  these  proceed  with 
spiral  circulations ;  in  the  former  they  are  against  the  hands  of  the 
watch,  and  in  the  latter  contrariwise.  The  tracks  of  storms  then  go 
eastward  in  both  hemispheres. 

The  writer  has  established  meteorological  stations  of  the  second 
order  at  Belem,  the  capital  of  the  State  of  Grao  Pard,  and  at  Mangos, 
the  capital  of  the  State  of  Amazonas,  in  Brazil.  After  a  series  of 
observations  shall  have  been  made,  it  may  be  possible  to  connect  the 
general  atmospheric  movements  of  both  hemispheres.  More  stations 
will  soon  be  in  operation. 

When  I  was  at  the  International  Conference  in  Munich  two  years 
ago,  Mr.  Wragge,  of  Brisbane,  Australia,  had  already  spoken  to  me 
about  my  giving  him,  by  telegraph,  information  as  to  the  southwest 
storms  which  pass  over  Brazil  and  which  afterward  cross  over  to 
those  regions.  In  my  opinion  the  meteorological  service  of  the  world, 
and  more  particularly  the  route  of  the  storms,  will  have  taken  a 
great  step  to  become  better  known,  when,  at  a  given  hour,  the  di- 
rectors of  the  various  meteorological  services  of  the  world  may  be 
able  to  communicate  with  one  another  at  a  certain  time  (noon  Green- 
wich) and  study  the  various  evolutions  of  capricious  storms  over  the 
face  of  the  terrestrial  globe.  A  strict  method  in  the  observations, 
the  mode  of  effecting  the  same,  the  development  of  the  network  of 
telegraphic  stations,  and  a  discussion  in  each  of  the  countries  where 
observations  are  taken  in  order  that  they  may  be  subsequently  sub- 


206  CHICAGO    METEOROLOGICAL    CONGKESS. 

mitted  to  and  appreciated  by  the  permanent  committee  of  meteor- 
logists,  all  this  will  be  a  great  advance  toward  determining  the  general 
laws  of  storms  in  the  South  Atlantic,  and  also  for  those  of  the  whole 
world. 

The  small  number  of  South  American  stations,  the  little  reliance 
on  the  old  instruments,  and  the  manner  of  setting  them  up  and  ob- 
serving them  are  sufficient  reasons  for  declaring  this  knowledge  still 
in  a  state  of  embryo  in  the  South  Atlantic,  and,  unfortunately,  very 
little  can  as  yet  be  said  upon  the  subject  even  after  consulting  the 
few  reports  here  referred  to:  C.  F.  Martins  (Amazonas),  1831;  Mar- 
tin de  Moussi  (Montevideo),  1843-52;  Doazan  (Buenos  Ayres),  1866; 
Albert  de  Lisle  (Montevideo),  1866;  Manuel  Eguia  (Buenos  Ayres), 
1875;  Morskoi  Sbornik  (Valparaiso),  1874. 

Let,  therefore,  the  above  proposition  go  forth  from  the  midst  of  this 
important  conference,  and  for  the  realization  of  my  scheme  I  call  to' 
my  assistance  the  Congress  Auxiliary  of  the  World's  Columbian  Ex- 
position. 

BND  OF  PART  I. 


JUL  72 


i;-;;;M;;!i-niMSWli 


